[Python-Dev] PEP 376 and PEP 302 - allowing import hooks to provide distribution metadata

[Tarek Ziadé]

On Sun, Jul 5, 2009 at 3:27 PM, Paul Moore<p.f.moore at gmail.com> wrote:
>>
>> A concrete proposal would be to take back your proposal, but return
>> tuples with the location as the first member.
>> e.g. "(location, relative path[s])"
>
> That sounds reasonable. So we can forget the "local" parameter, and
> return a tuple:
>
> - absolute location of the container (directory, zipfile or whatever
> containing the egginfo file) as a filesystem path in canonical native
> form (where it's filesystem based) or as an opaque token for the odd
> cases (frozen modules, for example) where a filesystem location isn't
> available.
> - entry from the RECORD file, as a slash-separated filename relative
> to the root of the container.

exactly,

>
> But if you're using get_installed_files(), why would you then want to
> read the files? What exactly would you *use* get_installed_files for
> which would then leave you needing to read the files? If it's to check
> they haven't changed (by comparing md5 values) you're doing that to
> uninstall, so that's the responsibility of the uninstall function.
>
> Again, it's a question of what is a public API, and what is the use
> case it's designed for.

Right. These APIs were created for third-party package managers.
One use case of a package manager is the uninstallation, but I have no other
use case in mind.

>
> I'm currently writing a SQLite importer, which will allow me to store
> "files" in any sort of database tables I want, so I can build in some
> nice pathological behaviour. That should tease out some awkward corner
> cases :-)

Sounds good.

Semi-related: even if the files themselves are in the filesystem,
having a sqlite db to
index the list of installed distributions makes a good cache solution
to reduce the disk I/O
and speed up the query functions.

So maybe we could use a disk-based cache for site-packages-like
directories in the
form of a sqlite db. That's what I am experimenting on my side.


>
> Paul
>



-- 
Tarek Ziadé | http://ziade.org