[Distutils] Why is zc.buildout picking the wrong platform for binary eggs?

[Martin Aspeli]

Martin Aspeli wrote:
> Hi,
> 
> As some of you may know, using lxml on OSX is a big pain because of an 
> incompatible system version of libxml2. The solution is to ship binary 
> eggs, which we already do for Windows.
> 
> Now, as a first test, Stefan has uploaded this egg:
> 
>    lxml-2.2.1-py2.4-macosx-10.5-i386.egg
> 
> See http://pypi.python.org/pypi/lxml/2.2.1
> 
> Now, I'm on OSX 10.5, and I've requested this exact version.
> 
> In a virtualenv, this works. It downloads the given binary egg.
> 
> In a buildout, it's preferring to download and build the egg itself, and 
> it calls it lxml-2.2.1-py2.4-macosx-10.3-i386.egg. That's weird, because 
> this machine has never had OSX 10.3 on it. :(
> 
> My Python 2.4.6 is installed via darwinports.
> 
> Now, I can probably work around this, but we're trying to ensure that 
> people have a sane lxml egg that will install cleanly on a number of 
> platforms. It's therefore pretty important that the average user doesn't 
> get this.
> 
> So, I'd like to try and figure out what's going on. How does buildout 
> decide which egg to look for? Why is easy_install in a virtualenv 
> behaving differently to my buildout?

Okay - I just wiped my parts/, bin/ and .installed.cfg and ran bootstrap 
again. This time, it's building an egg called 10.5, but it's still 
building its own from the source rather than downloading the binary egg. :(

Martin

-- 
Author of `Professional Plone Development`, a book for developers who
want to work with Plone. See http://martinaspeli.net/plone-book