On 7/24/2010 6:25 AM, Mark Lawrence wrote:
On 24/07/2010 04:17, Edward Diener wrote:
Are there any documents about multiple versionsof Python coexisting in
the same OS ( Windows in my case ) and what pitfalls to look out for ? I
have already run into a number of them. I installed Python 2.7 and 3.1.2
into completely folders, but immediately ran into serious problems
executing a Python script.
The first problem is that just invoking Python will start whichever
version is first in the PATH, and this is true from the command line or
internally in a Python script.
The second problem is that invoking a script ( some xxx.py ) will start
whichever version of Python is associated with the .py extension.
The third problem is if some software expects its scripts, which it puts
in some Python subdirectory to be in the PATH.
There may be other considerations but overall having to versions
coexisting has turned out to be a big headache involving both changes in
the PATH and in the .py association.
Does anybody know of other things to look out for ?
I found this only yesterday and found it extremely helpful, find the
post by Gabriel Genellina.
http://www.eggheadcafe.com/software/aspnet/35716114/maintain-2-versions-of-py.aspx
I found the solutions too exotic for actual use, and completely
ineffectual for the cases I originally cited. The people in that thread
seem to have completely forgotten that Python can be invoked externally
and internally both through executing 'python(w) xxx' and through
executing a file with the file extension(s) associated with Python. They
seem to have forgotten this can be within scripts or any other program
using Python, both written by themselves and by others, and not just by
their typing 'python(w) xxx' somewhere. Their solutions seem to believe
that only they will externally be i9nvoking Python and only for their
own written scripts, as opposed to the many libraries using Python as
well as the Python distribution itself.
The best solution is some program which changes the PATH and the Python
file type associations depending on which version of Python one wants to
use on one's own system when more than one Python version must coexist
with others. I will probably write such a program for myself.
Are the .py and .pyc extensions the only ones which are associated with
Python or are there others, for a normal Python installation in Windows ?
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