|Version Management with CVS - the CVS manual|
by Per Cederqvist et al.
Paperback (6"x9"), 216 pages, 8 figures
RRP £19.95 ($29.95)
1.2 What is CVS not?
CVS can do a lot of things for you, but it does not try to be everything for everyone.
- CVS is not a build system.
Though the structure of your repository and modules
file interact with your build system
(e.g. ‘Makefile’s), they are essentially
CVS does not dictate how you build anything. It
merely stores files for retrieval in a tree structure
CVS does not dictate how to use disk space in the
checked out working directories. If you write your
‘Makefile’s or scripts in every directory so they
have to know the relative positions of everything else,
you wind up requiring the entire repository to be
If you modularize your work, and construct a build
system that will share files (via links, mounts,
VPATHin ‘Makefile’s, etc.), you can arrange your disk usage however you like. But you have to remember that any such system is a lot of work to construct and maintain. CVS does not address the issues involved. Of course, you should place the tools created to support such a build system (scripts, ‘Makefile’s, etc) under CVS. Figuring out what files need to be rebuilt when something changes is, again, something to be handled outside the scope of CVS. One traditional approach is to use
makefor building, and use some automated tool for generating the dependencies which
makeuses. See section 14 How your build system interacts with CVS, for more information on doing builds in conjunction with CVS.
- CVS is not a substitute for management.
- Your managers and project leaders are expected to talk to you frequently enough to make certain you are aware of schedules, merge points, branch names and release dates. If they don't, CVS can't help. CVS is an instrument for making sources dance to your tune. But you are the piper and the composer. No instrument plays itself or writes its own music.
- CVS is not a substitute for developer communication.
When faced with conflicts within a single file, most
developers manage to resolve them without too much
effort. But a more general definition of "conflict"
includes problems too difficult to solve without
communication between developers.
CVS cannot determine when simultaneous changes
within a single file, or across a whole collection of
files, will logically conflict with one another. Its
concept of a conflict is purely textual, arising
when two changes to the same base file are near enough
to spook the merge (i.e.
diff3) command. CVS does not claim to help at all in figuring out non-textual or distributed conflicts in program logic. For example: Say you change the arguments to function
Xdefined in file ‘A’. At the same time, someone edits file ‘B’, adding new calls to function
Xusing the old arguments. You are outside the realm of CVS's competence. Acquire the habit of reading specs and talking to your peers.
- CVS does not have change control
Change control refers to a number of things. First of
all it can mean bug-tracking, that is being able
to keep a database of reported bugs and the status of
each one (is it fixed? in what release? has the bug
submitter agreed that it is fixed?). For interfacing
CVS to an external bug-tracking system, see the
‘rcsinfo’ and ‘verifymsg’ files
(see section B Reference manual for Administrative files).
Another aspect of change control is keeping track of
the fact that changes to several files were in fact
changed together as one logical change. If you check
in several files in a single
cvs commitoperation, CVS then forgets that those files were checked in together, and the fact that they have the same log message is the only thing tying them together. Keeping a GNU style ‘ChangeLog’ can help somewhat. Another aspect of change control, in some systems, is the ability to keep track of the status of each change. Some changes have been written by a developer, others have been reviewed by a second developer, and so on. Generally, the way to do this with CVS is to generate a diff (using
diff) and email it to someone who can then apply it using the
patchutility. This is very flexible, but depends on mechanisms outside CVS to make sure nothing falls through the cracks.
- CVS is not an automated testing program
It should be possible to enforce mandatory use of a
test suite using the
commitinfofile. I haven't heard a lot about projects trying to do that or whether there are subtle gotchas, however.
- CVS does not have a built-in process model
- Some systems provide ways to ensure that changes or releases go through various steps, with various approvals as needed. Generally, one can accomplish this with CVS but it might be a little more work. In some cases you'll want to use the ‘commitinfo’, ‘loginfo’, ‘rcsinfo’, or ‘verifymsg’ files, to require that certain steps be performed before cvs will allow a checkin. Also consider whether features such as branches and tags can be used to perform tasks such as doing work in a development tree and then merging certain changes over to a stable tree only once they have been proven.
|ISBN 0954161718||Version Management with CVS - the CVS manual||See the print edition|