[Distutils] setuptools: why does it install ctypes twice?
Phillip J. Eby
pje at telecommunity.com
Tue Nov 7 17:49:08 CET 2006
At 04:47 PM 11/7/2006 +0100, Victor Stinner wrote:
>My problem is that "sudo ./setup.py install" reinstall ctypes 1.0.1 and
>ElementTree 1.2.6 whereas they are already installed by Ubuntu (using
setuptools isn't installing these things twice, it's installing them
once. It can't detect that Ubuntu has already installed them, if they are
installed without .egg-info files or directories. Python 2.5 does this
automatically for any distutils-installed package, but for older versions
of Python you need to manually create these files in site-packages if you
want to ensure that another copy doesn't get installed:
The content of each file should be that package's PKG-INFO file. This will
allow setuptools to detect what versions are installed.
The alternative of course is just to let the second installation happen.
Still another alternative would be to create a tool for Debian/Ubuntu users
that would generate the .egg-info files automatically, although I'm not
sure how practical that is, since Debian package names do not map 1:1 with
PyPI package names, and the installed packages do not include PKG-INFO files.
Essentially, this is a design flaw of Debian packaging policy for Python,
which has not been updated to deal with distutils' project-oriented nature
or the existence of PyPI. Debian requirements are expressed in terms of
Python packages, rather than in terms of Python *projects*. Python
projects are the unit of distribution and cataloguing, whereas Python
packages are code units, and can be split across projects as well as having
more than one in a given project. This problem is independent of
setuptools per se, but the flaw is more clearly visible when you try to use
setuptools in conjunction with it.
More information about the Distutils-SIG