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

[Michael Foord]

--
http://www.ironpythoninaction.com

On 14 Jul 2009, at 01:12, "Sridhar Ratnakumar"  
<sridharr at activestate.com> wrote:

> 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'?
>

An abomination for which I am truly sorry - however to be precise I'm  
pretty sure the setup.py specifies configobj and it is only registered  
on PyPI with mixed case (which I don't believe I can change).

Michael




>> 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
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