CVu-Mercurial: Hg.tex annotate

annotate Hg.tex @ 10:2e4d690ffabb

Tart up PDF output with clickable links and doc info.

author	Jim Hague <jim.hague@acm.org>
date	Fri, 22 May 2009 11:04:47 +0100
parents	2155510c62f3
children	03d0ebf7ce0b

rev	line source
9 2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	1 \documentclass[a4paper]{article}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	2 \usepackage{pslatex}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	3 \usepackage{url}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	4
10 2e4d690ffabb Tart up PDF output with clickable links and doc info. Jim Hague <jim.hague@acm.org> parents: 9 diff changeset	5 \usepackage[pdftex]{hyperref}
2e4d690ffabb Tart up PDF output with clickable links and doc info. Jim Hague <jim.hague@acm.org> parents: 9 diff changeset	6 \hypersetup{
2e4d690ffabb Tart up PDF output with clickable links and doc info. Jim Hague <jim.hague@acm.org> parents: 9 diff changeset	7 pdfauthor={Jim Hague},
2e4d690ffabb Tart up PDF output with clickable links and doc info. Jim Hague <jim.hague@acm.org> parents: 9 diff changeset	8 pdftitle={Inside a distributed version control system},
2e4d690ffabb Tart up PDF output with clickable links and doc info. Jim Hague <jim.hague@acm.org> parents: 9 diff changeset	9 colorlinks}
2e4d690ffabb Tart up PDF output with clickable links and doc info. Jim Hague <jim.hague@acm.org> parents: 9 diff changeset	10
9 2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	11 \newcommand{\standout}[1]{
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	12 {\begin{center} \large \textbf{#1} \end{center}}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	13 }
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	14
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	15 \setlength{\parskip}{2mm}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	16 \setlength{\parindent}{0mm}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	17
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	18 \begin{document}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	19 \title{Inside a distributed version control system}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	20 \author{Jim Hague\\
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	21 \texttt{jim.hague@acm.org}}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	22 \date{May 2009}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	23 \maketitle
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	24
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	25 \section{Preamble}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	26 Grinton Lodge is a Youth Hostel that sits on an exposed hillside just
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	27 above the small hamlet of Grinton in Swaledale, in the Yorkshire Dales
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	28 National Park. A former Victorian shooting lodge, it now welcomes
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	29 walkers and other travellers from around the world.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	30
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	31 Tonight, a Wednesday in mid-November, is not one of its busiest
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	32 nights. Kat, the duty staff member, tells me that there is a small
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	33 corporate team-building group in the annex. There's no sign of them at
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	34 present. Otherwise, that portion of the world that has beaten a path
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	35 to the door of this grand building today consists of just me. And Kat
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	36 goes home soon.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	37
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	38 The November CVu, removed from its wrappers and read yesterday, lies
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	39 in my bag. Taunting me. Go on, it says, if you've ever going to put
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	40 finger to keyboard in the name of CVu, well, tonight you are out of
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	41 excuses.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	42
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	43 Bugger.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	44
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	45 \section{Let's look into Mercurial}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	46 If you're at all interested in version control systems~--- and any
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	47 software developer not using one daily is a strange beast indeed~---
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	48 you'll at least have become vaguely aware in the last few years of the
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	49 growing maturity of the latest group of version control systems
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	50 offering funky new stuff. These are the distributed version control
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	51 systems (DVCS). There is more to them than just their headline
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	52 attributes, being able to check history and do checkins while
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	53 disconnected from a central server, but these are damm useful to start
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	54 with.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	55
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	56 When I first heard about DVCS, it wasn't immediately obvious to me (to
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	57 put it mildly) how they would work. After years of using a centralised
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	58 version control system, I had rough mental model of what went on. But
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	59 how do you cope without the central server forcing ordering onto the
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	60 changes?
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	61
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	62 Since then I've started using Mercurial\footnote{
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	63 \url{http://www.selenic.com/mercurial}}.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	64 Mercurial is a DVCS. It's one of
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	65 three DVCSs that have gained significant popularity in the last few
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	66 years, the other two being Git\footnote{\url{http://git-scm.com}} and
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	67 Bazaar\footnote{\url{http://bazaar-vcs.org/}}.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	68 I switched a significant work project over
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	69 to Mercurial (from Subversion) in mid-2007, because a customer site
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	70 required on-site work but could not allow access back to the company
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	71 VPN. I chose Mercurial for a variety of reasons which I won't bore you
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	72 with here\footnote{
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	73 OK, if you must know:
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	74 \begin{itemize}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	75 \item Implementability. I needed the system to work on Windows, Linux and
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	76 AIX. The latter was not one of the directly supported platforms for
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	77 any of the candidates. Git's implementation uses a horde of
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	78 tools. Bazaar requires only Python, but required Python 2.4 while IBM
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	79 stubbornly still supplies only Python 2.3. Mercurial requires Python
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	80 2.3 or greater, and uses some C for speed.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	81 \item Simplicity. My users used Subversion daily, but did not generally
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	82 have much experience with other VCS. From the command line,
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	83 Mercurial's core operations will be familiar to a Subversion
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	84 user. This is also true of Bazaar, but was less true of Git. Git has
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	85 improved in this matter since then, but a Mr Winder of this parish
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	86 tells me that it's still possible to seriously embarrass
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	87 yourself. There was also a lack of Windows support for Git at the
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	88 time.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	89 \item Speed. Mercurial is fast. In the same ballpark as Git. Bazaar
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	90 wasn't, and although it has improved significantly, has, in my
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	91 estimation, added user complexity in the process, and at the time
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	92 of writing is still off the pace for some operations.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	93 \item Documentation. At the time, Bryan O'Sullivan's excellent Mercurial
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	94 book (\url{http://hgbook.red-bean.com}) was a clear winner for best
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	95 documentation.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	96 \end{itemize}}.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	97
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	98 What I want to do in this article is give you an insight into how a
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	99 DVCS works. OK, so specifically I'm going to be talking about
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	100 Mercurial, but Git and Bazaar attack the problem in a similar way. But
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	101 first I'd better give you some idea of how you use Mercurial.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	102
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	103 \subsection{The 5 minute Mercurial overview}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	104 \subsubsection{The basics}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	105 I think it unlikely that someone possessing the taste and discernment
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	106 to be reading CVu would not be familiar with at least one version
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	107 control system. So, while I want to give you a flavour of what it's
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	108 like to use, I'm not going to hang about. If you'd like a proper
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	109 introduction, or you don't follow something, I thoroughly recommend
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	110 you consult the Mercurial book.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	111
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	112 To start using Mercurial to keep track of a project.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	113
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	114 \begin{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	115 $ hg init
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	116 $
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	117 \end{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	118
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	119 This creates the repository root in the current directory.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	120
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	121 Like CVS\footnote{\url{http://www.nongnu.org/cvs/}}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	122 with its \texttt{CVS} directory and
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	123 Subversion\footnote{\url{http://subversion.tigris.org/}}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	124 with its \texttt{.svn}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	125 directory, Mercurial keeps its private data in a directory. Mercifully there is
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	126 only one of these, in the top level of your project. And rather than
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	127 holding details of where the actual repository is to be found, the \texttt{.hg}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	128 directory holds the entire repository.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	129
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	130 Next you need to specify the files you want Mercurial to track.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	131
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	132 \begin{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	133 $ echo "There was a gibbon one morning" > pome.txt
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	134 $ hg add pome.txt
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	135 $
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	136 \end{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	137
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	138 As you might expect, this marks the files as to be added. And as you
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	139 might also expect, you need to commit to record the added files in the
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	140 repository. The commit comment can be supplied on the command line; if
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	141 you don't supply a comment, you'll be dropped into an editor to
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	142 provide one.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	143
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	144 There is a suggested format for these messages~--- a one line summary
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	145 followed by any more required detail on following lines. By default
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	146 Mercurial will only display the first line of commit messages when
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	147 listing changes. In these examples I'll stick to terse messages, and
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	148 I'll enter them from the command line.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	149
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	150 \begin{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	151 $ hg commit -m "My Pome" -u "Jim Hague <jim.hague@acm.org>"
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	152 $
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	153 \end{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	154
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	155 Mercurial records the user making the change as part of the change
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	156 information. It is usual to give your name and email address as I've
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	157 done here. You can imagine, though, that constantly having to repeat
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	158 this is a bit tedious, so you can set a default user name in a
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	159 configuration file. Mercurial keeps global, user and repository
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	160 configurations, and it can go in any of those.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	161
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	162 As with Subversion, after further edits you see how your working copy
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	163 differs from the repository.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	164
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	165 \begin{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	166 $ hg status
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	167 M pome.txt
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	168 $ hg diff
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	169 diff -r 33596ef855c1 pome.txt
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	170 --- a/pome.txt Wed Apr 23 22:36:33 2008 +0100
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	171 +++ b/pome.txt Wed Apr 23 22:48:01 2008 +0100
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	172 @@ -1,1 +1,2 @@ There was a gibbon one morning
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	173 There was a gibbon one morning
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	174 +said "I think I will fly to the moon".
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	175 $ hg commit -m "A great second line"
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	176 $
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	177 \end{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	178
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	179 And look through a log of changes.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	180
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	181 \begin{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	182 $ hg log
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	183 changeset: 1:3d65e7a57890
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	184 tag: tip
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	185 user: Jim Hague <jim.hague@acm.org>
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	186 date: Wed Apr 23 22:49:10 2008 +0100
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	187 summary: A great second line
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	188
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	189 changeset: 0:33596ef855c1
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	190 user: Jim Hague <jim.hague@acm.org>
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	191 date: Wed Apr 23 22:36:33 2008 +0100
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	192 summary: My Pome
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	193
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	194 $
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	195 \end{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	196
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	197 There are some items here that need an explanation.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	198
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	199 The changeset identifier is in fact two identifiers separated by a
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	200 colon. The first is the sequence number of the changeset in the
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	201 repository, and is directly comparable to the change number in a
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	202 Subversion repository. The second is a globally unique identifier for
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	203 that change. As the change is copied from one repository to another
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	204 (this is a distributed system, remember, even if we haven't come to
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	205 that bit yet), its sequence number in any particular repository will
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	206 change, but the global identifier will always remain the same.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	207
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	208 \texttt{tip} is a Mercurial term. It means simply the most recent change.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	209
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	210 Want to rename a file?
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	211
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	212 \begin{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	213 $ hg mv pome.txt poem.txt
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	214 $ hg status
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	215 A poem.txt
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	216 R pome.txt
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	217 $ hg commit -m "Rename my file"
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	218 $
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	219 \end{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	220 (The command to rename a file is actually \texttt{hg rename},
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	221 but Mercurial saves Unix-trained fingers from
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	222 typing embarrassment.)
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	223
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	224 At this point you may be wondering about directories. \texttt{hg mkdir}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	225 perhaps? Well, no. Mercurial only tracks files. To be sure, the
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	226 directory a file occupies is tracked, but effectively only as a
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	227 component of the file name. This has the slightly unexpected result
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	228 that you can't record an empty directory in your repository.\footnote{
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	229 I tripped over this converting a work Subversion
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	230 repository. One possibility is to create a placeholder file in the
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	231 directory. In the event I created the directory (which receives build
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	232 products) as part of the build instead.}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	233
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	234 Given this, and the status output above that suggests strongly that
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	235 Mercurial treats a rename as a copy followed by a delete, you may be
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	236 worried that Mercurial won't cope at all well with rearranging your
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	237 repository. Relax. Mercurial does store the details of the rename as
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	238 part of the changeset, and copes very well with rearrangements\footnote{
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	239 The Mercurial designers justify not dealing with
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	240 directories as first class objects by pointing out that provided you
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	241 can correctly move files about in the tree, the other reasons for
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	242 tracking directories are uncommon and do not in their opinion justify
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	243 the considerable added complexity. So far I've found no reason to
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	244 doubt that judgement.}.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	245
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	246 Want to rewind the working copy to a previous revision?
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	247
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	248 \begin{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	249 $ hg update -r 1
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	250 1 files updated, 0 files merged, 1 files removed, 0 files unresolved
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	251 $
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	252 \end{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	253
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	254 \texttt{hg update} updates the working files. In this case I'm specifying
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	255 that I want to go back to local changeset 1. I could also have typed
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	256 \texttt{-r 3d65e7a57890}, or even \texttt{-r 3d};
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	257 when specifying the global change
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	258 identifier you only need to type enough digits to make it unique.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	259
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	260 This is all very well, but it's not exactly distributed, is it?
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	261
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	262 \subsubsection{Going distributed}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	263 A version control system goes Distributed by allowing multiple copies
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	264 of the repository to exist, and work to be done in all those
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	265 repositories in parallel. So when you start work on an existing
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	266 project, the first thing to do is to get your own copy of the
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	267 repository.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	268
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	269 \begin{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	270 elsewhere$ hg clone ssh://jim.home.net/Poem Jim-Poem
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	271 updating working directory
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	272 1 files updated, 0 files merged, 0 files removed, 0 files unresolved
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	273 \end{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	274
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	275 Mercurial lets you access other repositories via the file system, over http or
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	276 over ssh.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	277
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	278 \begin{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	279 elsewhere$ cd Jim-Poem
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	280 elsewhere$ hg log
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	281 changeset: 3:a065eb26e6b9
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	282 tag: tip
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	283 user: Jim Hague <jim.hague@acm.org>
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	284 date: Thu Apr 24 18:52:31 2008 +0100
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	285 summary: Rename my file
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	286
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	287 changeset: 2:ff97668b7422
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	288 user: Jim Hague <jim.hague@acm.org>
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	289 date: Thu Apr 24 18:50:22 2008 +0100
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	290 summary: Finished first verse
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	291
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	292 changeset: 1:3d65e7a57890
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	293 user: Jim Hague <jim.hague@acm.org>
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	294 date: Wed Apr 23 22:49:10 2008 +0100
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	295 summary: A great second line
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	296
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	297 changeset: 0:33596ef855c1
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	298 user: Jim Hague <jim.hague@acm.org>
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	299 date: Wed Apr 23 22:36:33 2008 +0100
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	300 summary: My Pome
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	301
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	302 $
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	303 \end{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	304
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	305 \texttt{hg clone} is aptly named. It creates a new repository that contains
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	306 exactly the same changes as the source repository. You can make a
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	307 clone just by copying your project directory, if you're confident
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	308 nothing else will access it during the copy. \texttt{hg clone} saves you this
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	309 worry, and sets the default push/pull location in the new repo to the
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	310 cloned repo.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	311
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	312 From that point, you use \texttt{hg pull} to collect changes from other
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	313 places into your repo (though note it does not by default update your
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	314 working copy), and, as you might guess, \texttt{hg push} shoves your changes
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	315 into a foreign repository. By default these will act on the repository
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	316 you cloned from, but you can specify any other repository.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	317
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	318 More on those in a moment. First, though, I want to show you something
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	319 you can't do in Subversion. Start with the repository with 4 changes
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	320 we just cloned. I want to focus on the first couple of lines, so I'll
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	321 wind the working copy back to the point where only those lines exist.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	322
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	323 \begin{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	324 $ hg update -r 1
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	325 1 files updated, 0 files merged, 1 files removed, 0 files unresolved
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	326 $
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	327 \end{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	328
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	329 And make a change.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	330
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	331 \begin{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	332 $ hg diff
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	333 diff -r 3d65e7a57890 pome.txt
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	334 --- a/pome.txt Wed Apr 23 22:49:10 2008 +0100
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	335 +++ b/pome.txt Thu Apr 24 19:13:14 2008 +0100
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	336 @@ -1,2 +1,2 @@ There was a gibbon one morning
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	337 -There was a gibbon one morning
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	338 -said "I think I will fly to the moon".
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	339 +There was a baboon who one afternoon
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	340 +said "I think I will fly to the sun".
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	341 $ hg commit -m "Better first two lines"
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	342 $
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	343 \end{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	344
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	345 The alert among you will have sat up at that. Well done! Yes, there's
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	346 something very worrying. How can I commit a change at an old point?
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	347 If you try this in Subversion, it will complain mightily about your
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	348 file being out of date. But Mercurial just went ahead and did
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	349 something. The Bazaar experts among you will know that in Bazaar, if
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	350 you use \texttt{bzr revert -r} to bring the working copy to a past revision,
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	351 make a change and commit, then your latest version will be the past
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	352 revision plus your change. Perhaps that's what Mercurial did?
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	353
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	354 No. What Mercurial did is central to Mercurial's view of the
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	355 world. You took your working copy back to an old changeset, and then
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	356 committed a fresh change based at that changeset. Mercurial actually
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	357 did just what you asked it to do, no more and no less. Let's see the
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	358 initial evidence.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	359
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	360 \begin{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	361 $ hg heads
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	362 changeset: 4:267d32f158b3
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	363 tag: tip
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	364 parent: 1:3d65e7a57890
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	365 user: Jim Hague <jim.hague@acm.org>
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	366 date: Thu Apr 24 19:13:59 2008 +0100
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	367 summary: Better first two lines
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	368
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	369 changeset: 3:a065eb26e6b9
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	370 user: Jim Hague <jim.hague@acm.org>
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	371 date: Thu Apr 24 18:52:31 2008 +0100
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	372 summary: Rename my file
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	373
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	374 $
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	375 \end{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	376
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	377 Time for some more Mercurial terminology. You can think of a \texttt{head} in
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	378 Mercurial as the most recent change on a branch. In Mercurial, a
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	379 branch is simply what happens when you commit a change that has as its
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	380 parent a change that already has a child. Mercurial has a standard
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	381 extension \texttt{hg glog} which uses some ASCII art to show the current
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	382 state:
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	383
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	384 \begin{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	385 $ hg glog
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	386 @ changeset: 4:267d32f158b3
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	387 \| tag: tip
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	388 \| parent: 1:3d65e7a57890
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	389 \| user: Jim Hague <jim.hague@acm.org>
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	390 \| date: Thu Apr 24 19:13:59 2008 +0100
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	391 \| summary: Better first two lines
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	392 \|
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	393 \| o changeset: 3:a065eb26e6b9
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	394 \| \| user: Jim Hague <jim.hague@acm.org>
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	395 \| \| date: Thu Apr 24 18:52:31 2008 +0100
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	396 \| \| summary: Rename my file
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	397 \| \|
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	398 \| o changeset: 2:ff97668b7422
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	399 \|/ user: Jim Hague <jim.hague@acm.org>
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	400 \| date: Thu Apr 24 18:50:22 2008 +0100
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	401 \| summary: Finished first verse
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	402 \|
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	403 o changeset: 1:3d65e7a57890
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	404 \| user: Jim Hague <jim.hague@acm.org>
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	405 \| date: Wed Apr 23 22:49:10 2008 +0100
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	406 \| summary: A great second line
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	407 \|
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	408 o changeset: 0:33596ef855c1
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	409 user: Jim Hague <jim.hague@acm.org>
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	410 date: Wed Apr 23 22:36:33 2008 +0100
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	411 summary: My Pome
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	412
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	413 $
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	414 \end{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	415
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	416 \texttt{hg view} shows a nicer graphical view\footnote{Though, being
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	417 Tcl/Tk based, not that much nicer.}.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	418
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	419 So the change is in there. It's the latest change, and is simply on a
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	420 different branch to the other changes.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	421
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	422 Almost invariably, you will want to bring everything back together and
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	423 merge the branches. A merge is a change that combines two heads back
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	424 into one. It prepares an updated working directory with the merged
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	425 contents of the two heads for you to review and, if satisfactory,
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	426 commit.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	427
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	428 \begin{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	429 $ hg merge
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	430 merging pome.txt and poem.txt
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	431 0 files updated, 1 files merged, 0 files removed, 0 files unresolved
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	432 (branch merge, don't forget to commit)
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	433 $ cat poem.txt
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	434 There was a baboon who one afternoon
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	435 said "I think I will fly to the sun".
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	436 So with two great palms strapped to his arms,
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	437 he started his takeoff run.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	438 $ hg commit -m "Merge first line branch"
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	439 $
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	440 \end{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	441
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	442 (I'm no poet. The poem is, of
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	443 course, \textit{Silly Old Baboon} by the late, great, Spike
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	444 Milligan. From \textit{A Book of Milliganimals}, Puffin, 1971.)
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	445
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	446 Here's the ASCII art again showing what just happened.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	447 Oh, and notice in the above that Mercurial has done the
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	448 right thing with regard to the rename.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	449
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	450 \begin{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	451 $ hg glog
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	452 @ changeset: 5:792ab970fc80
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	453 \|\ tag: tip
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	454 \| \| parent: 4:267d32f158b3
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	455 \| \| parent: 3:a065eb26e6b9
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	456 \| \| user: Jim Hague <jim.hague@acm.org>
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	457 \| \| date: Thu Apr 24 19:29:53 2008 +0100
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	458 \| \| summary: Merge first line branch
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	459 \| \|
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	460 \| o changeset: 4:267d32f158b3
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	461 \| \| parent: 1:3d65e7a57890
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	462 \| \| user: Jim Hague <jim.hague@acm.org>
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	463 \| \| date: Thu Apr 24 19:13:59 2008 +0100
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	464 \| \| summary: Better first two lines
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	465 \| \|
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	466 o \| changeset: 3:a065eb26e6b9
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	467 \| \| user: Jim Hague <jim.hague@acm.org>
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	468 \| \| date: Thu Apr 24 18:52:31 2008 +0100
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	469 \| \| summary: Rename my file
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	470 \| \|
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	471 o \| changeset: 2:ff97668b7422
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	472 \|/ user: Jim Hague <jim.hague@acm.org>
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	473 \| date: Thu Apr 24 18:50:22 2008 +0100
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	474 \| summary: Finished first verse
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	475 \|
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	476 o changeset: 1:3d65e7a57890
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	477 \| user: Jim Hague <jim.hague@acm.org>
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	478 \| date: Wed Apr 23 22:49:10 2008 +0100
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	479 \| summary: A great second line
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	480 \|
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	481 o changeset: 0:33596ef855c1
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	482 user: Jim Hague <jim.hague@acm.org>
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	483 date: Wed Apr 23 22:36:33 2008 +0100
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	484 summary: My Pome
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	485
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	486 $
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	487 \end{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	488
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	489 So, our little branch change has now been merged back, and we have a
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	490 single line of development again. Notice that unlike the other
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	491 changesets, changeset 5 has two parent changesets, indicating it is a
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	492 merge changeset. You can only merge two branches in one operation; or
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	493 putting it another way, a changeset can have a maximum of two parents.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	494
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	495 This behaviour is absolutely central to Mercurial's philosophy. If a
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	496 change is committed that takes as its starting point a change that
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	497 already has a child, then a branch gets created. Working with
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	498 Mercurial, branches get created frequently, and equally frequently
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	499 merged back. As befits any frequent operation, both are easy to do.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	500
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	501 You're probably thinking at this point that this making a commit onto
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	502 an old version is a slightly strange thing to do, and you'd be right.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	503 But that's exactly what's going to happen the moment you go
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	504 distributed. Two people working independently with their own
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	505 repositories are going to make commits based, typically, on the latest
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	506 changes they happen to have incorporated into their tree. To be
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	507 Distributed, a DVCS has to deal with this. Mercurial faces it head-on.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	508 When you pull changes into your repo (or someone else pushes them), if
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	509 any of the changes overlap~--- are both based on the same base change~---
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	510 you get extra heads, and it's up to you to let these extra heads live
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	511 or merge, as you please.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	512
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	513 In practice this is more manageable then you might think. Consider a
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	514 typical Mercurial usage, where the 'master' repo sits on a known
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	515 server, and everyone pulls changes from the master and pushes their
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	516 own efforts to the master. But default Mercurial won't let you push if
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	517 the receiving repo will gain an extra head as a result, so you
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	518 typically pull (and do any required merging) just before
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	519 pushing. Subversion users will recognised this pattern. Subversion
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	520 won't let you commit a change if your working copy is not at the very
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	521 latest revision, so the Subversion user will update, and merge if
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	522 necessary, just before committing.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	523
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	524 What, then, about a branch in the conventional sense of '1.0
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	525 maintenance branch'? Typically in Mercurial you'd handle this by
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	526 keeping a separate cloned repository for those changes. Cloning is
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	527 fast, and if local uses hard links where possible on filesystems that
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	528 support them, so isn't necessarily extravagant on disc space. You can,
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	529 if you prefer, handle them all in a single repo with 'named
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	530 branches', but cloning is definitely simpler.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	531
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	532 OK, so now you know the basics of using Mercurial. We can proceed to
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	533 looking at how this magic is achieved. In particular, where does this
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	534 magic globally unique identifier for a change come from?
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	535
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	536 \subsection{Inside the Mercurial repo}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	537 The way Mercurial handles its repo is really quite simple.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	538
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	539 That's simple, as in 'most things are simple once you know the
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	540 answer'. I found the explanation helpful\footnote{For the curious,
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	541 Bryan O'Sullivan's excellent Mercurial book
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	542 has a chapter on the subject, and the Mercurial website has a fair amount
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	543 of detail too.}, so this section attempts
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	544 the 10,000ft (FL100 if you prefer) view of Mercurial.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	545
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	546 First remember that any file or component can only have one or two
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	547 parents. You can't merge more than one other branch at once.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	548
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	549 We start with the basic building block, which Mercurial calls a
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	550 revlog. A revlog is a thing that holds a file and all the changes in
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	551 the file history\footnote{For any non-trivial file, this will
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	552 actually be two files on the disc, a data file and an index.}. The
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	553 revlog stores the differences between successive versions
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	554 of the file, though it will periodically store a complete version of
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	555 the file instead of a difference, so that the content of any
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	556 particular file version can always be reconstructed without excessive
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	557 effort.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	558
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	559 Under the secret-squirrel Mercurial \texttt{.hg} directory at the top of your
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	560 project is a store which holds a revlog for each file in your
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	561 project. So you have the complete history of the project locally. No
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	562 more round trips to the server.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	563
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	564 Both the differences between successive versions and the periodic
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	565 complete versions of a file are compressed before storing. This is
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	566 surprisingly effective at minimising the storage requirements this
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	567 entire history of your project. I have a small Java project handy,
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	568 comprising a little over 300 source modules. There are 5 branches plus
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	569 the mainline, and some 1920 commits in all. A Subversion checkout of
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	570 the current mainline takes 51Mb. Converting the project to Mercurial
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	571 yields a Mercurial repository that takes 60Mb, so a little
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	572 bigger. Remember, though, that the Mercurial repository includes not
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	573 just the working copy, but also the entire history of the project.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	574
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	575 Any point in the evolution of a revlog can be uniquely identified with
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	576 a nodeid. This is simply the SHA1 hash of the current file contents
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	577 concatenated with the nodeids of one or both parents of the current
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	578 revision. Note that this way, two file states are identical if and
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	579 only if the file contents are the same and the file has the
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	580 same history.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	581
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	582 Here's a dump of a revlog index:
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	583
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	584 \begin{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	585 $ hg debugindex .hg/store/data/pome.txt.i
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	586 rev offset length base linkrev nodeid p1 p2
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	587 0 0 32 0 0 6bbbd5d6cc53 000000000000 000000000000
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	588 1 32 51 0 1 83d266583303 6bbbd5d6cc53 000000000000
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	589 2 83 84 0 2 14a54ec34bb6 83d266583303 000000000000
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	590 3 167 76 3 4 dc4df776b38b 83d266583303 000000000000
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	591 $
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	592 \end{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	593
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	594 Note here that a file state can have two parents. If both the parent
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	595 nodeids are non-null, the file state has two parents, and the state is
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	596 therefore the result of a merge.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	597
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	598 Let's dump out a revlog at a particular revision:
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	599
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	600 \begin{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	601 $ hg debugdata .hg/store/data/pome.txt.i 2
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	602 There was a gibbon one morning
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	603 said "I think I will fly to the moon".
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	604 So with two great palms strapped to his arms,
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	605 he started his takeoff run.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	606 $
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	607 \end{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	608
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	609 The next component is the manifest. This is simply a list of all the
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	610 files in the project, together with their current nodeids. The
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	611 manifest is a file, held in a revlog. The nodeid of the manifest,
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	612 therefore, identifies the project filesystem at a particular point.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	613
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	614 \begin{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	615 $ hg debugdata .hg/store/00manifest.i 5
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	616 poem.txt5168b1a5e2f44aa4e0f164e170820845183f50c8
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	617 $
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	618 \end{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	619
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	620 Finally we have the changeset. This is the atomic collection of
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	621 changes to a repository that leads to a new revision. The changeset
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	622 info includes the nodeid of the corresponding manifest, the timestamp
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	623 and committer ID, a list of changed files and a comment. The changeset
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	624 also includes the nodeid of the parent changeset, or the two parents
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	625 if the change is a merge. The changeset description is held in a
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	626 revlog, the changelog.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	627
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	628 \begin{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	629 $ hg debugdata .hg/store/00changelog.i 5
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	630 1ccc11b6f7308cc8fa1573c2f3811a4710c91e3e
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	631 Jim Hague <jim.hague@acm.org>
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	632 1209061793 -3600
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	633 poem.txt
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	634 pome.txt
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	635
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	636 Merge first line branch
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	637 $
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	638 \end{verbatim}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	639
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	640 The nodeid of the changeset, therefore, gives us a globally unique
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	641 identifier for any particular change. Changesets have a
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	642 Subversion-like incrementing change number, but it is peculiar to that
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	643 repository. The nodeid, however, is global.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	644
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	645 One more detail remains to complete the picture. How do we get back
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	646 from a particular file change to find the responsible changeset? Each
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	647 revlog change has a linkrev entry that does just this.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	648
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	649 So, now we have a repository with a history of the changes applied to
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	650 that repository. Each change has a unique identifier. If we find that
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	651 change in another repository, it means that at the point in the other
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	652 repository we have exactly the same state; the file contents and
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	653 history are identical.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	654
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	655 At this point we can see how pulling changes from another repository
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	656 works. Mercurial has to determine which changesets in the source
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	657 repository are missing in the target repository. To do this, for each
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	658 head in the source repo it has to find the most recent change in that
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	659 head that it already present in the target repo, and get any remaining
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	660 changes after that point. These changes are then copied over and
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	661 applied.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	662
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	663 The Mercurial revlog format has proved remarkably durable. Since the
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	664 first release of Mercurial in April 2005, these have been a total of 5
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	665 changes to the file format. However, of those, all but one have been
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	666 changes to the handling of file names. The most recent change, in
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	667 October 2008, and its predecessor in December 2006, were both
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	668 introduced purely to cope with Windows specific issues. The one change
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	669 that touched the data structures described above was in April 2006. The
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	670 format introduced, RevLogNG, changed only the details of index data
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	671 held, not the overall design. The chief Mercurial developer, Matt
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	672 Mackall, notes that the code in present-day Mercurial devoted to
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	673 reading the old format comprises 28 lines of Python. Compared with,
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	674 say, the early tribulations of Subversion and the switch from \texttt{bdfs} to
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	675 \texttt{fsfs}, this is an impressive record.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	676
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	677 \section{Reflections on going distributed}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	678 It's nearly traditional at this stage in an introduction to DVCS to
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	679 demonstrate several different workflow scenarios that you can build
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	680 with a DVCS. Which makes the important point that a DVCS can be
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	681 adapted to your workflow in a way that is at best unwieldy with a
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	682 CVCS. I intend, though, to break with tradition here.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	683
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	684 By this stage, I hope you can see that distributing version control
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	685 works by introducing branches where development takes place in
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	686 parallel. Mercurial treats these branches as arising naturally from
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	687 the commits made and transferred between repositories. Both Git and
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	688 Bazaar take a slightly different viewpoint, and explicitly generate a
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	689 fresh branch for work in a particular repositories. But in both cases
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	690 the underlying principle of identifying changes by a globally unique
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	691 identifier and resolving parallel development by merges between
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	692 overlapping changes is the same. And all three can be used in a truly
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	693 distributed manner, with full history and the ability to commit being
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	694 available locally.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	695
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	696 So instead of chatter on about workflows, I want instead to reflect on
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	697 the consequences all this has for that all-important question of
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	698 whether a DVCS is a suitable vehicle for your data.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	699
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	700 The first is a minor and rather obvious point. If you want to store
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	701 files that are very large and which change often in your DVCS, then
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	702 all the compression in the world is unlikely to stop the storage
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	703 requirements for the full project history from becoming uncomfortably
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	704 large, particularly if the files are not very compressible to start
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	705 with.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	706
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	707 The second, and main, point is that there is an important question you
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	708 need to ask about your data. We've seen that a DVCS relies on
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	709 branching and merging to weave its magic. So take a close look at your
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	710 data, and ask:
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	711
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	712 \standout{Will It Merge?}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	713
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	714 The subset of plain old text which comprises program source
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	715 code requires some human oversight, but will merge automatically
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	716 well enough for the process to be well within the bounds of the
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	717 possible.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	718
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	719 Unfortunately when we move further afield mergeability becomes a rarer
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	720 commodity. I nearly began the previous paragraph by stating that
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	721 plain old text will merge well enough. Then Doubt set in~--- what about
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	722 XML? Or BASE64 encoded content?
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	723
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	724 Of course, merge doesn't necessarily have to be textual merge. I am
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	725 told that Word can be used to diff and merge two Word \texttt{.doc} files, a
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	726 data format notorious for its binary impenetrability. As long as some
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	727 suitable merge agent is available, and the DVCS can be configured to
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	728 use it for data of a particular type\footnote{Mercurial can have the
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	729 merge and diff tools specified with reference to the file extension on
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	730 which they operate~--- I assume Bazaar and Git are similar.}, then there
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	731 is no bar to successful DVCS use.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	732
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	733 Before this reliance on mergeability causes you to dismiss DVCS out of
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	734 hand, reflect. A CVCS can only handle non-mergeable data by acting as
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	735 a versioned file store; in other words, having as the only available
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	736 merge option the use of one or other of the merge candidates in its
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	737 entirety. Useful though a versioned file store can be, it cannot be
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	738 considered a full-featured version control system. By treating the
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	739 offending unmergeable files as external to the DVCS, or with careful
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	740 workflow~--- disabling the distributed and mergeable potentials~--- a DVCS
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	741 can deal with these files, but only at a cost of its distributedness
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	742 or its version control system-ness. In this it differs little from a
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	743 CVCS.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	744
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	745 So, for all data you want to version control, let your battle cry be:
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	746
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	747 \standout{Will It Merge?}
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	748
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	749 At this point, I have an urge to don lab coat and safety goggles and
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	750 be videoed attempting to mechanically merge data in a variety of
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	751 different formats. Frankly, this is unlikely to be as exciting at
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	752 blending iPhones\footnote{\url{http://www.willitblend.com}},
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	753 but from a system development point of view it's rather more
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	754 important. And, I think gives us a large clue as to one of the
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	755 reasons for the continuing
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	756 popularity of Plain Old Text as a source code representation mechanism.
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	757
2155510c62f3 A version formatted with Latex. And spellchecked. Jim Hague <jim.hague@acm.org> parents: diff changeset	758 \end{document}

Mercurial > CVu-Mercurial

annotate Hg.tex @ 10:2e4d690ffabb