On Fri, 29 Oct 2010 04:07:15 -0700 Chris Rebert <c...@rebertia.com> wrote:
> On Fri, Oct 29, 2010 at 4:02 AM, Antoine Pitrou <solip...@pitrou.net> wrote: > > On Sun, 24 Oct 2010 10:48:23 +0200 > > "Martin v. Loewis" <mar...@v.loewis.de> wrote: > >> > >> You may now wonder whether it is possible to set __context__ to None > >> somehow. See PEP 3134: > >> > >> Open Issue: Suppressing Context > >> > >> As written, this PEP makes it impossible to suppress '__context__', > >> since setting exc.__context__ to None in an 'except' or 'finally' > >> clause will only result in it being set again when exc is raised. > > > > It is not easily discoverable, but it is possible to suppress > > __context__ by using a bare re-raise afterwards: > > > >>>> try: > > ... try: 1/0 > > ... except ZeroDivisionError: raise KeyError > > ... except BaseException as e: > > ... e.__context__ = None > > ... raise > > ... > > Traceback (most recent call last): > > File "<stdin>", line 3, in <module> > > KeyError > > So, how/why does that work? A bare "raise" simply re-raises the currently known exception without changing anything (neither the traceback nor the context). This __context__ problem is mostly theoretical, anyway. If you want to present exceptions to users in a different way, you can write a catch-all except clause at the root of your program and use the traceback module to do what you want. Regards Antoine. -- http://mail.python.org/mailman/listinfo/python-list
