Re: [matplotlib-devel] Add some caching to texmanager.py?

[Nicholas Y. <su...@su...>]

On Thu, 2005-06-23 at 10:58 -0600, Fernando Perez wrote:
> Nicholas Young wrote:
> > On Wed, 2005-06-22 at 11:45 -0600, Fernando Perez wrote:
> > 
> >>os.environ['TEXMFOUTPUT'] = '/some/path'
> > 
> > 
> > According to the online docs
> > (http://docs.python.org/lib/os-procinfo.html) setting os.environ isn't
> > safe/available for all platforms.  You can use the subprocess module to
> > set the environment of a subprocess under python 2.4 but I don't think
> > there's a simple way to do this and capture the output for earlier
> > versions.
> 
> Well, after reading that I get that os.environ _is_ writable everywhere, it's 
> just that it may leak memory in OSX/BSD.  What's not always available is the 
> putenv() call, but python will find its way around it if needed.

To quote "If putenv() is not provided, this mapping may be passed to the
appropriate process-creation functions to cause child processes to use a
modified environment.".  To me this implies that you have to pass
os.environ to a process-creation function supporting the env keyword
(os.execve, etc.) none of which seem to support capturing output.  On
the other hand does anyone actually run mpl on a platform which doesn't
support putenv?

> Since this would be a once-only call, I think that leaking a few bytes is an 
> acceptable price to pay to prevent a crash if the user happens to be 
> positioned on a non-writable dir.

After reading an online copy of the freebsd man putenv it actually reads
"Successive calls to setenv() or putenv() assigning a differently sized
value to the same name will result in a memory leak." so setting this
once wouldn't be a problem.

So I was wrong and setting os.environ seems reasonable in this case -
but it seems sensible to be aware of the potential for causing problems
if anyone trys to get mpl working on an odd platform.

Nick