[Python-Dev] PEP 376 - from PyPM's point of view

[Sridhar Ratnakumar]

Here are my comments regarding PEP 376 with respect to PyPM (the Python
package manager being developd at ActiveState)


Multiple versions: I understand that the PEP does not support
installation (thus uninstallation) of multiple versions of the same
package. Should this be explicitly mentioned in the PEP -- as
`get_distribution` API accepts only `name` argument, and not a `version`
argument?

> get_distribution(name) -> Distribution or None.
>Scans all elements in sys.path and looks for all directories ending
> with .egg-info. Returns a Distribution corresponding to the .egg-info
> directory that contains a PKG-INFO that matches name for the name
> metadata.
>Notice that there should be at most one result. The first result
> founded is returned. If the directory is not found, returns None.

Some packages have package names with mixed case. Example: ConfigObj
.. as registered in setup.py. However, other packages such as turbogears
specifies "configobj" (lowercase) in their install_requires.

Is `get_distribution(name)` supposed to handle mixed cases? Will it
match both 'ConfigObj' and 'configobj'?

> get_installed_files(local=False) -> iterator of (path, md5, size)

Will this also return the directories /created/ during the installation?
For example, will it also contain the entry "docutils" .. along with
"docutils/__init__.py"?

If not, how is the installer (pip, pypm, etc..) supposed to know which
directories to remove (docutils/) and which directories not to remove
(site-packages/, bin/, etc..)?

> The new version of PEP 345 (XXX work in progress) extends the Metadata
> standard and fullfills the requirements described in PEP 262, like the
> REQUIRES section.

Can you tell more about this?

I see that PEP 262 allows both distributions names ('docutils') and
modules/packages ('roman.py') in the 'Requires:' section. Is this how
the new PEP is going to adhere to? Or, is it going to adhere to PEP
345's way of allowing *only* modules/packages?

In practice, I noticed that packages usually specify distribution names
in their 'Requires:' file (or install_requires.txt in the case of
setuptools). Hence, PyPM *assumes* the install requirements to be
distribution name. But then .. most distributions have the same name as
their primary module/package.

Ok, so PEP 345 also specifies the 'Provides:' header. Does
easy_install/pip make use 'Provides:' at all when resolving
dependencies? For example, does 'pip install sphinx' go look for all
distributions that 'provides' the 'docutils' provision.. or does it
simply get the distribution named 'docutils'?

-srid