[Distutils] Buildout not updating setuptools

[Phillip J. Eby]

At 07:33 AM 7/9/2007 -0400, Jim Fulton wrote:

>On Jul 8, 2007, at 12:56 PM, Phillip J. Eby wrote:
>
>>At 07:17 AM 7/8/2007 -0400, Jim Fulton wrote:
>>>So, the Ubuntu packager for setuptools decided not to install
>>>setuptools as an actual egg, but as a wonky sort-of develop egg with
>>>a less than ideal location.
>>>
>>>IMO, this is just wrong and broken. Does anyone disagree?
>>
>>Yes, because it's fine for them to install it as a develop egg;
>>that's how system packages are *supposed* to be installed.
>
>Really? Why?  If this is true, then "develop" seems to be a misnomer.

Yep - which is why I've been referring to them as "egg-info" or 
"single version, externally managed" eggs.  :)

The code still uses one symbol for DEVELOP_DIST because the selection 
precedence of such eggs is the same, regardless of whether they're 
generated by "install" or "develop".


>>If you want to be able to figure out if something is really a
>>"develop" installation, you need to look for an .egg-link file, not
>>the mere existence of a DEVELOP_DIST egg.  Only the "develop"
>>command writes .egg-link files.
>
>But you can't look for an egg-link file if all you have is a
>distribution.  The dist location points to the contents of the egg
>link file.  How is one to determine, given a DEVELOP_DIS egg in an
>environment whether it was created by the develop command?

I didn't say it was easy.  ;)  You'd have to check for .egg-link 
files along the environment path, and see if there's one that points 
to the distribution in question.

One possible distinction is that distutils generates .egg-info 
*files* with version information in the file name, and setuptools 
"install" and bdist packages include the version information in the 
directory name by default.  So you can rule out any egg for which a 
versioned filename exists as not being "develop" targets.

Unfortunately, you can't assume the reverse: just because it's an 
.egg-info directory and *doesn't* have any version information, you 
don't know for sure that it was generated by develop.  It could be a 
system package produced by one of those people who likes to tinker, 
and decided to remove the version info from the directory name for 
some crazy reason.  OTOH, you could just say the heck with 'em.  :)

You can easily check whether the .egg-info is a file: if it's a 
DEVELOP_DIST, and ``dist.list_metadata('')`` contains 1 or 0 entries, 
it's a metadata file, and definitely not a develop.

In order to check the directory version info, you'll have to steal a 
peak at the ``dist._provider.egg_info`` path and see if it's got a 
'-' in it before the '.'.  If yes, it's not a "develop"-generated egg.