1 CVS Cheat Sheet for fptools hackers.
2 ------------------------------------
4 At Glasgow, we use CVS (Concurrent Version System) to keep track of
5 our sources for various software projects. CVS lets several people
6 work on the same software at the same time, allowing changes to be
7 checked in incrementally.
9 The full documentation for CVS is online, in info format (use 'info
10 cvs' or run emacs and type C-h i). A good source of tips is the CVS
11 FAQ, in /local/doc/gnu/CVS.FAQ.
13 This note is supposed to be a set of guidelines for how to use CVS at
14 Glasgow, and will probably evolve in time. The main thing to remember
15 is that most mistakes can be undone, but if there's anything you're
16 not sure about feel free to bug the local CVS meister (namely Me
17 <simonm@dcs.gla.ac.uk>).
19 The following guidelines should mean we don't step on each other's
20 toes too much. Ok, here's what you do:
22 * Firstly, identify which areas of the source tree you'll be working
23 on. The directory structure looks like this:
26 fptools/hslibs Haskell Libraries
29 fptools/green-card Green Card
30 fptools/nofib Nofib test suite
31 fptools/common-rts GHC/Hugs combined run-time system
33 For each directory, there's a mailing list: fp-cvs-ghc,
34 fp-cvs-hslibs etc. Everyone on the mailing list is sent a message
35 automatically by CVS whenever someone checks in a change, this helps
36 to keep track of what's going on when several people are working on
37 related stuff. Ask the CVS meister to put you on the relevant
40 * Create a .cvsrc file. Mine looks like this:
47 It just gives default flags for some of the CVS commands. For instance,
48 the -P flag to 'checkout' says prune empty directories, which is
49 normally what you want.
51 * Check out your sources. The Approved Way (at least by me) to do
54 $ CVSROOT=/local/fp/src/cvsroot
57 or, if you're using csh or tcsh:
58 $ setenv CVSROOT=/local/fp/src/cvsroot
60 $ cvs checkout fpconfig
62 At this point you have a new directory called 'fptools' which contains
63 the basic stuff for the fptools suite - including the configuration
64 files and literate programming tools.
66 $ mv fptools <directory>
68 You can call the fptools directory whatever you like, CVS won't mind.
71 $ cvs checkout ghc hslibs happy
73 The second command here checks out the relevant modules you want to
74 work on. For a GHC build, for instance, you need at least ghc and
77 * Build the software, if necessary. Unless you're just working on
78 documentation, you'll probably want to build the software in order
79 to test any changes you make. For GHC, instructions can be found
80 in the GHC installation guide, online in info format.
82 * Make changes. Preferably small ones first.
84 * Test them. You can see exactly what changes you've made by using
85 the 'cvs diff' command. For example,
89 lists all the changes (using the 'diff' command) in and below the
90 current directory. In emacs, C-c C-v C-= runs 'cvs diff' on the current
91 buffer and shows you the results.
93 * Before checking in a change, you need to update your source tree:
98 This pulls in any changes that other people have made, and merges them
99 with yours. If there are any conflicts, CVS will tell you, and you'll
100 have to resolve them before you can check your changes in. The
101 documentation describes what to do in the event of a conflict.
103 It's not always necessary to do a full cvs update before checking in
104 a change, since CVS will always tell you if you try to check in a file
105 that someone else has changed. However, you should still update
106 at regular intervals to avoid making changes that don't work in
107 conjuction with changes that someone else made. Keeping an eye on
108 what goes by on the mailing list can help here.
110 * When you're happy that your change isn't going to break anything,
111 check it in. For a one-file change:
113 $ cvs commit <filename>
115 CVS will then pop up an editor for you to enter a "commit message",
116 this is just a short description of what your change does, and will
117 be kept in the history of the file.
119 If you're using emacs, simply load up the file into a buffer and type
120 C-x C-q, and emacs will prompt for a commit message and then check in
123 For a multiple-file change, things are a bit trickier. There are
124 several ways to do this, but this is the way I find easiest.
125 First type the commit message into a temporary file. Then either
127 $ cvs commit -F <commit-message> <file_1> .... <file_n>
129 or, if nothing else has changed in this part of the source tree,
131 $ cvs commit -F <commit-message> <directory>
133 where <directory> is a common parent directory for all your changes,
134 and <commit-message> is the name of the file containing the commit
137 Shortly afterwards, you'll get some mail from the relevant mailing
138 list saying which files changed, and giving the commit message.
139 For a multiple-file change, you should still get only *one* message.
141 * As a general rule: commit changes in small units, preferably
142 addressing one issue or implementing a single feature. Provide a
143 descriptive log message so that the repository records exactly which
144 changes were required to implement a given feature/fix a bug. I've
145 found this *very* useful in the past for finding out when a particular
146 bug was introduced: you can just wind back the CVS tree until
149 * Keep the sources at least *buildable* at any given time. No
150 doubt bugs will creep in, but it's quite easy to ensure that any
151 change made at least leaves the tree in a buildable state. We do
152 nightly builds of GHC to keep an eye on what things work/don't work
153 each day and how we're doing in relation to previous verions. This
154 idea is truely wrecked if the compiler won't build in the first place!
156 Ok, that'll do for now.
158 Simon Marlow <simonm@dcs.gla.ac.uk>