But inspect is in the stdlib. Surely changing inspect.py is less controversial than amending the semantics of frame objects.
On Thu, Mar 6, 2014 at 10:10 AM, Xavier Morel <python-...@masklinn.net>wrote: > On 2014-03-06, at 16:52 , Antoine Pitrou <solip...@pitrou.net> wrote: > > Le 06/03/2014 16:03, Yury Selivanov a écrit : > >> > >> On 2014-03-06, 8:42 AM, Antoine Pitrou wrote: > >>> Le 05/03/2014 23:53, Nick Coghlan a écrit : > >>>> > >>>> __traceback__ wouldn't change [...] > >>> > >>> Uh, really? If you want to suppress all reference cycles, you *have* > >>> to remove __traceback__. > >>> > >>> The problem is to make computation of the traceback summary > >>> lightweight enough that it doesn't degrade performance in the common > >>> case where you don't have to print the traceback later. > >> > >> So why can't we allow instantiation of types.TracebackType & > >> types.FrameType? > > > > IMO it is absolutely out of question to allow creation of arbitrary > frames from Python code, because the structure and initialization of frames > embody too many low-level implementation details. > > > > We might allow the creation of traceback objects, but without any custom > frame objects it is unclear how useful that would be. > > Some bits of the standard library (and probably third-party libraries > transitively relying on getinnerframes) really, really want traceback > objects and can't be used with a stack or frames extracted via > inspect.currentframe() or whatever. For instance cgitb.text calls > inspect.getinnerframes which accesses param.tb_frame then calls > getframeinfo(param). getframeinfo blows up if it does not get either an > actual traceback object or an actual frame object. > > A frame object does not have a tb_frame attribute, and will thus fail > in getinnerframes, a fake traceback object will fail in getframeinfo. > > Therefore it's not possible to call cgitb.text outside of an exception > handling context (that is, not possible to use it as a > traceback.print_stack providing extra information). If it were possible > to create traceback objects, there would be no issue there at least. > _______________________________________________ > Python-Dev mailing list > Python-Dev@python.org > https://mail.python.org/mailman/listinfo/python-dev > Unsubscribe: > https://mail.python.org/mailman/options/python-dev/guido%40python.org > -- --Guido van Rossum (python.org/~guido)
_______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
