[Python-Dev] when is path==NULL?

Christian Heimes lists at cheimes.de
Tue Sep 30 14:48:40 CEST 2008

Ulrich Eckhardt wrote:
> Hi!
> I'm looking at trunk/Python/sysmodule.c, function PySys_SetArgv(). In that 
> function, there is code like this:
>   PyObject* path = PySys_GetObject("path");
>   ...
>   if (path != NULL) {
>     ...
>   }
> My intuition says that if path==NULL, something is very wrong. At least I 
> would expect to get 'None', but never NULL, except when out of memory. So, 
> for the case that path==NULL', I would simply invoke Py_FatalError("no mem 
> for sys.path"), similarly to the other call there.

PySys_GetObject may return NULL after the user has removed sys.path with 
delattr(sys, 'path'). There are valid applications for removing sys.path.


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