sys.stderr and PyErr_WriteUnraisable

[Gabriel Genellina]

En Tue, 15 Dec 2009 11:17:20 -0300, Jan Langer  
<jan.langer at etit.tu-chemnitz.de> escribió:

> from test.test_support import captured_output
> with captured_output("stderr") as stderr:
>      def g():
>          try:
>              g()
>          except RuntimeError,e:
>              pass
>      g()
>      print stderr.getvalue()
>
> I expect the ignored exceptions to be printed into the StringIO object  
> stderr. With this code there are no warnings on the command line, but  
> getvalue() returns nothing.

If sys.stderr is not a real file, no error gets printed.
PyErr_WriteUnraisable calls PyFile_WriteString, which checks for non-file  
objects and only writes to them when no error is set.
Seems to be a safety measure.

-- 
Gabriel Genellina