[Python-checkins] CVS: python/nondist/peps pep-0250.txt,NONE,1.1
Wed, 18 Apr 2001 03:28:13 -0700
Update of /cvsroot/python/python/nondist/peps
In directory usw-pr-cvs1:/tmp/cvs-serv1982
PEP 250, Using site-packages on All Platforms, Paul Moore
--- NEW FILE: pep-0250.txt ---
Title: Using site-packages on All Platforms
Version $Revision: 1.1 $
Author: firstname.lastname@example.org (Paul Moore)
Type: Standards Track
The standard Python distribution includes a directory
Lib/site-packages, which is used on Unix platforms to hold
locally-installed modules and packages. The site.py module
distributed with Python includes support for locating other
modules in the site-packages directory.
This PEP proposes that the site-packages directory should be used
uniformly across all platforms for locally installed modules.
On Windows platforms, the default setting for sys.path does not
include a directory suitable for users to install locally
developed modules. The "expected" location appears to be the
directory containing the Python executable itself. Including
locally developed code in the same directory as installed
executables is not good practice.
Clearly, users can manipulate sys.path, either in a locally
modified site.py, or in a suitable sitecustomize.py, or even via
.pth files. However, there should be a standard location for such
files, rather than relying on every individual site having to set
their own policy.
In addition, with distutils becoming more prevalent as a means of
distributing modules, the need for a standard install location for
distributed modules will become more common. It would be better
to define such a standard now, rather than later when more
distutils-based packages exist which will need rebuilding.
It is relevant to note that prior to Python 2.1, the site-packages
directory was not included in sys.path for Macintosh platforms.
This has been changed in 2.1, and Macintosh includes sys.path now,
leaving Windows as the only major platform with no site-specific
The implementation of this feature is fairly trivial. All that
would be required is a change to site.py, to change the section
setting sitedirs. The Python 2.1 version has
if os.sep == '/':
sitedirs = [makepath(prefix,
"python" + sys.version[:3],
makepath(prefix, "lib", "site-python")]
elif os.sep == ':':
sitedirs = [makepath(prefix, "lib", "site-packages")]
sitedirs = [prefix]
A suitable change would be to simply replace the last 4 lines with
sitedirs == [makepath(prefix, "lib", "site-packages")]
Changes would also be required to distutils, in the sysconfig.py
file. It is worth noting that this file does not seem to have
been updated in line with the change of policy on the Macintosh,
as of this writing.
1. It would be better if this change could be included in Python
2.1, as changing something of this nature is better done
sooner, rather than later, to reduce the backward-compatibility
burden. This is extremely unlikely to happen at this late stage
in the release cycle, however.
2. This change does not preclude packages using the current
location -- the change only adds a directory to sys.path, it
does not remove anything.
3. In the Windows distribution of Python 2.1 (beta 1), the
Lib\site-packages directory has been removed. It would need to
This document has been placed in the public domain.