[Distutils] working-env.py

[Ian Bicking]

I wrote a script last night that implements some of the ideas of a 
working environment, similar in goals to virtual-python.py, but it 
doesn't actually work like that. 
http://svn.colorstudy.com/home/ianb/working-env.py

When you run "python working-env.py env" you get:

env/
   bin/
     activate (something you source in your shell to activate this 
environment)
   conf/
   src/
   lib/python2.4/
     distutils/__init__.py
     distutils/distutils.cfg
     setuptools/__init__.py
     setuptools.pth
     site.py


You activate the environment by adding env/lib/python2.4 to your 
PYTHONPATH, and maybe adding env/bin/ to your PATH.

The custom site.py accomplishes most of the work, I guess.  It's just 
like the normal site.py, except it doesn't add site-packages (I should 
probably make an option so you can set it up either way). 
distutils/__init__.py is Ronald Oussoren's suggestion for monkeypatching 
distutils.  It both manages to get the working environment's 
distutils.cfg to be used (comes for free, since distutils.dist looks 
alongside distutils.__file__), and it substitutes __WORKING__ for the 
actual working directory.

The setuptools monkeypatch changes how scripts are generated.  But I 
don't like how it works.  It changes scripts to look more like:

   #!/usr/bin/python -S
   import sys, os
   join, dirname = os.path.join, os.path.dirname
   lib_dir = join(dirname(dirname(__file__)), 'lib', 'python%s.%s' % 
tuple(sys.version_info[:2]))
   sys.path.insert(0, lib_dir)
   import site
   ... normal stuff ...

Monkeypatching distutils is fine, because it's not going anywhere, but 
monkeypatching setuptools is not going to be so reliable.  But I guess 
we just need to figure out exactly what we want to do, then move those 
changes to setuptools.  Also, distutils should probably be monkeypatched 
directly in some fashion, so that distutils install also installs 
scripts with this header.

A goal I have -- that is pretty much accomplished so far -- is that the 
working environment be movable, and all paths be relative.  But 
setuptools creates some absolute directory names in .pth files, I believe.

-- 
Ian Bicking  |  ianb at colorstudy.com  |  http://blog.ianbicking.org