Phillip J. Eby wrote: > At 11:21 AM 3/21/2008 -0500, [EMAIL PROTECTED] wrote: >> Joachim> I think, the uninstall should _not_ 'rm -rf' but only 'rm' the >> Joachim> files (and 'rmdir' directories, but not recursively) that it >> Joachim> created, and that have not been modified in the meantime (after >> Joachim> the installation). >> >> That's not sufficient. Suppose file C (e.g. /usr/local/etc/mime.types) is >> in both packages A and B. >> >> Install A - this will create C >> Install B - this might overwrite C, saving a copy, or it might retain >> A's copy. >> Uninstall B - this has to know that C is used by A and not touch it > > Correct. However, in practice, B should not touch C, unless the file > is shared between them. > > This is a key issue for support of namespace packages, at least if we > want to avoid using .pth files. (Which is what setuptools-built > system packages do for namespace packages currently.) > > Of course, one possible solution is for both A and B to depend on a > "virtual package" that contains C, such that both A and B can install > it if it's not there, and list it in their dependencies. But this is > one of the handful of open issues that needs to be resolved with Real > Life Package Management people, such as Debian, Fedora, etc.
I've always thought that the right way to handle the dependency DAG is to treat it as a garbage collection problem. Assume that for each package there is a way to derive the following two pieces of information: (a) whether this package was installed explicitly by the user, or implicitly as the result of a dependency, and (b) the set of dependencies for this package. Then, starting with the list of 'explicit' packages as the root set, do a standard mark & sweep; Any package not marked is a candidate for removal. -- Talin _______________________________________________ Distutils-SIG maillist - Distutils-SIG@python.org http://mail.python.org/mailman/listinfo/distutils-sig
