[Catalog-sig] Distinguishing PEP 345 distributions from old ones.

Tarek Ziadé tarek at ziade.org
Thu May 24 15:55:08 CEST 2012

On 5/24/12 3:49 PM, Alexis Métaireau wrote:
> Le 24/05/2012 15:26, Tarek Ziadé a écrit :
>> On 5/24/12 3:07 PM, Alexis Métaireau wrote:
>>>> the metadata version, which is 1.2
>>> That doesn't seem to be available in PyPI direclty, nor via the 
>>> XML-RPC interface: http://pypi.python.org/pypi/pelican/json
>>>>>> import xmlrpclib
>>>>>> client = xmlrpclib.ServerProxy('http://pypi.python.org/pypi')
>>>>>> client.release_data('Pelican', '2.8.1')/keys()
>> Weird, I could have swore it was in there. We should add the 
>> 'metadata_version' key.
>> In the interim you can detect when it's a 1.2 because it has specific 
>> fields , by loading the metadata in a packaging.metadata.Metadata 
>> instance
>> and ask it to detect the version.
> Oh, it seems that new distributions do have a "requires_dist" field, 
> so I can use this and determine if it's a PEP 345 dist or not from there.
> Well, I could if I had the metadata fields there, but they aren't 
> present (PyPI doesn't do anything with the setup.py to get the 
> metadata related fields it seems).
that's done on client side when you call "register", it sends the 
metadata as a dict

then PyPI just stores them into a SQL table - so the values that are 
kept are the one defined by the sql schema since it does not store a blob.

What we need to add is a feature at PyPI that extracts setup.cfg from 
the release, and make it available at an url

so if you have it you know it's the new standard,

> Using packaging/distutils2.metadata.Metadata to guess the version of 
> the metadata is thus not working for me when getting this metadata 
> from PyPI.
> For instance:
> >>> from distutils2.pypi import xmlrpc
> >>> rel = xmlrpc.Client().get_metadata('gitbuster', '2.1b7')
> >>> rel.metadata['metadata-version']
> >>> rel.metadata['requires-dist']
> ['gfbi_core (==0.5b6)', 'argparse']
> So I guess I will rely on having something in the "requires-dist" or 
> not to determine the version of the metadata for now..

Yes but if the project does not have any dependencies it won't work.

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