[Python-Dev] is this a bug? no environment variables

[Glenn Linderman]

On 11/22/2010 8:33 AM, Guido van Rossum wrote:
> On Sun, Nov 21, 2010 at 9:40 PM, Glenn Linderman<v+python at g.nevcal.com>  wrote:
>> In reviewing my notes from my experimentations with CGIHTTPServer
>> (Python2.6) and then http.server (Python 3.2a4), I note one behavior I
>> haven't reported as a bug, nor do I know where to start to figure it out,
>> other than experimentally.
>>
>> The experiment: launching CGIHTTPServer without environment variables, by
>> the simple expedient of using a batch file to unset all the existing
>> environment variables, and then launching Python2.6 with CGIHTTPServer.
>>
>> So it failed early: random.py fails at line 110 (Python 2.6).
> What specific traceback do you get? In my copy of the code that line says
>
>                  a = long(_hexlify(_urandom(16)), 16)
>
> and I could just imagine that _urandom() fails for some reason to do
> with the environment (it is a reference to os.urandom()), which, being
> part of the C library code, might depend on the environment.
>
> But you're not giving enough info to debug this.

Yep, that's the line.  I'll have to re-run the scenario, but will do it 
on 3.2a4, hopefully tonight or tomorrow, to get the traceback.


>> I suppose it is possible that some environment variables are used by Python
>> directly (but I can't seem to find a documented list of them) although I
>> would expect that usage to be optional, with fall-back defaults when they
>> don't exist.
> That is certainly the idea, but the fallbacks may not always be nice.
>
> Environment variables used by Python or the stdlib itself are supposed
> to be named PYTHON<whatever>  if they are Python-specific, and there's
> a way to disable all of these (-E). But there are other environment
> variables (HOME and PATH come to mind) that have a broader definition
> and that are used in some part of the stdlib. Plus, as I mentioned,
> who knows what the non-Python C library uses (well, somebody probably
> knows, but I don't know of a central source that we can actually trust
> across the many platforms where Python runs).

OK, thanks for the philosophy statement.  That's what I didn't know, 
being new.

>> I suppose it is even possible that some Windows APIs might
>> depend on some environment variables, but I expected that the registry had
>> replaced such usage completely, by now, with the environment variables
>> mostly being a convenience tool for batch files, or for optional, temporary
>> alteration of particular settings.
> That sounds like wishful thinking. :-)

Well, wishful thinking from me regarding the Windows and the registry is 
that Windows would be better off without a registry.  But it seemed like 
their direction was instead to do away with environment variables, but 
in any case, I have little idea if they've achieved it, but should have 
achieved something in 6.1 versions of Windows!
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