[Distutils] use of '_' in package name causing version parsing issue?

P.J. Eby pje at telecommunity.com
Tue Mar 9 23:24:18 CET 2010

At 03:03 PM 3/9/2010 -0600, Brad Allen wrote:
>Today I was informed of an issue in which buildout (with the latest
>setuptools) is not resolving version numbers properly, causing the
>wrong package to be selected in some cases. The cause identified was
>having '_' in the package name.

I suspect there is a miscommunication or misunderstanding 
somewhere.  It is perfectly acceptable to have a '_' in a package 
name or project name.  This:

>| >>> a="jiva_interface-2.3.6-py2.6.egg"
>| >>> b="jiva_interface-2.3.8-py2.6.egg"
>| >>> pkg_resources.parse_version(a)

Is the wrong API to use to parse an egg filename, as parse_version() 
is for parsing a version that's already extracted from a 
filename.  This is the right API for extracting a version from a filename:

 >>> pkg_resources.Distribution.from_filename(a).version
 >>> pkg_resources.Distribution.from_filename(b).version
 >>> pkg_resources.Distribution.from_filename(c).version
 >>> pkg_resources.Distribution.from_filename(d).version

And here's the correct one for extracting the parsed version from a filename:

 >>> pkg_resources.Distribution.from_filename(a).parsed_version
('00000002', '00000003', '00000006', '*final')
 >>> pkg_resources.Distribution.from_filename(b).parsed_version
('00000002', '00000003', '00000008', '*final')
 >>> pkg_resources.Distribution.from_filename(c).parsed_version
('00000000', '00000001', '00000001', '*final')
 >>> pkg_resources.Distribution.from_filename(d).parsed_version
('00000000', '00000001', '00000002', '*final')

As you can see, these APIs work just fine, so the example given is a 
red herring, unless Buildout is using the APIs incorrectly (which I 
really doubt it is).

Usually, the situation where people run into trouble with unusual 
package names or filenames is when they produce a source distribution 
manually, or by using something other than distutils/setuptools (that 
has different filename escaping rules), or when they manually rename 
a file before uploading, and expect it to still work the same.

It would be a good idea for you to check which of these things (if 
any) is taking place, and provide details of the specific problem, 
with steps to reproduce it, since the example given probably has 
nothing to do with it.  Thanks!

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