[Distutils] Re: [Python-Dev] Where to install non-code files

[Greg Ward]

On 26 May 2000, Gordon McMillan said:
> Hmm. I see an application as a module distribution that 
> happens to have a script. (Or maybe I see a module 
> distribution as a scriptless app ;-)).

But end-users who just want to run a Python application see it as an
application; the fact that it's (largely) written in Python and includes 
a Python library of its own is immaterial.  However, all files from that 
application should most likely be installed in the same place --
/usr/local/myapp or "C:\Program Files\MyApp", pick your poison.

And the module developer should have the option of just dumping his
stuff in /usr/local/lib/python1.x/site-packages and /usr/local/bin, or
C:\Python, or whatever is the locally appropriate place to dump Python
modules.  Currently, of course, that's the *only* option that the
Distutils easily supports.  (Although I suspect that with the current
code, one could craft a setup.cfg that forces the "install" command to
put files wherever you damn well please.  That's icky, though -- it
won't deal with setting the right sys.path for your application.)

[me]
> An idea AMK and I cooked up yesterday would be an addition
> to the Distutils "build_scripts" command: along with frobbing the
> #! line to point to the right Python interpreter, add a second
> line:
>   import sys ; sys.append(path-to-this-app's-python-lib)
> 
> Or maybe "sys.insert(0, ...)".

Oops, meant "sys.path..." there of course.

[Gordon]
> $PYTHONSTARTUP ??

The idea is to set sys.path for *just this application* rather than for
all Python code installed on the system.  This is kind of important if
you have an application that defines a module "DateTime" and another,
independent module called "DateTime".  /usr/local/myapp/lib/python
should come first in sys.path when you run myapp, and it should never be 
seen when you run anything else.

The possibilities are:
  * create shell script wrappers for every Python script: eg.
    script1 might be
    PYTHONPATH=/usr/local/myapp/lib/python \
      exec /usr/local/bin/python1.6 /usr/local/myapp/_script1.py

  * adjust the scripts at build time so set the right sys.path

Nasty as it is, I incline towards the latter: if nothing else, it's more 
portable!

But this is all speculative.  The immediate aim of the Distutils is
*not* full-blown Python applications, but I am starting to see how we
could support such applications.  A little idle speculation never hurt
anyone.

> That's an artifact of your code ;-). If you figured it out once, 
> you stand at least a 50% chance of getting the same answer 
> a second time <.5 wink>.

What!?!  Are you accusing me of writing complex code?
Well... ok... maybe a little bit... but only in install.py,
really... the rest of it's quite straightforward!

        Greg
-- 
Greg Ward - nerd                                        gward@python.net
http://starship.python.net/~gward/
I have many CHARTS and DIAGRAMS..