At 11:47 PM 2/6/2006 -0800, Bob Ippolito wrote:
>This sort must be used only with eggs that are compatible
>with the current architecture -- which means either "fat" or
>_macosx_arch(os.uname()[4].replace(' ', '_')). Also allowing
>_macosx_arch and universally allowing fat are going to require
>another patch to setuptools (that I have not yet written, because
>it's not the right thing to do until egg-sorting is right).
>
> # a and b must only differ in platform specifics!
> def cmp_platform_eggs(a, b):
> if a.arch == "fat" and b.arch == "fat":
> pass
> elif a.arch == "fat":
> return 1
> elif b.arch == "fat":
> return -1
> # lower version sorts higher
> return -cmp(a.macosx_version, b.macosx_version)
>
>This sort means that fat will always be preferred, and lower
>requirements sort higher. This makes it easier for people who wish
>to redistribute self-contained applications to other users (a la
>py2app, py2exe, cx_Freeze), which is a very important use case for
>this platform.
The way I'd recommend implementing this is via a _platform_key() function
that takes a platform string and converts it to something that sorts the
way you want it to; higher values are preferred to lower values. Note that
pkg_resources sorts distributions by version and other precedence
information first; platform is the very *last* thing considered in a
sort. It also can't be guaranteed that you'll be comparing your custom
object with a common platform. So please try to write the patch with these
constraints in mind. On the line that's currently line 1758 of
pkg_resources.py, you'll see a reference to 'self.platform'; change that to
'_platform_key(self.platform)' once you've got your precedence algorithm
figured out.
Note also that self.platform can be None, so _platform_key should not
assume its parameter is a string.
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