[Catalog-sig] PEP 345 Update

["Martin v. Löwis"]

> So, technically, all an installer has to do is avoid placing conflicting
> packages on the same runtime sys.path, in order to comply with Conflicts.

It should also make sure that they don't overwrite each other's files.

Then, it should also make sure that they aren't conflicting in any other
way, such as using the same relational database instance, creating the
same Unix account, listening to the same port, etc.

If two packages are marked as conflicting (by one of them), the
installer has really to trust this in the first place - only the
user installing the software might know even better.

> OTOH, if what it's saying is something like, "you can't import
> asyncore's mainloop and Twisted's mainloop at the same time and live",
> then what value does it have for the install tool, vs. merely informing
> the user?

There are many other ways in which software can conflict. E.g. on Linux
distributions, it is common that you can install only one MTA. You
can also install only one Apache MPM module in Debian.

Regards,
Martin