[Python-ideas] Yield-From: GeneratorReturn exception

Guido van Rossum guido at python.org
Sun Mar 29 04:52:44 CEST 2009

On Sat, Mar 28, 2009 at 8:00 PM, Nick Coghlan <ncoghlan at gmail.com> wrote:
> Greg Ewing wrote:
>> While attempting to update the PEP to incorporate a
>> GeneratorReturn exception, I've thought of a potential
>> difficulty in making the exception type depend on
>> whether the return statement had a value.
>> Currently the StopIteration exception is created after
>> the return statement has unwound the stack frame, by
>> which time we've lost track of whether it had an
>> expression.
> Does it become easier if "return None" raises StopIteration instead of
> raising GeneratorReturn(None)?
> I think I'd prefer that to having to perform major surgery on the eval
> loop to make it do something else... (Guido may have other ideas,
> obviously).

I think my first response on this (yesterday?) already mentioned that
I didn't mind so much whether "return None" was treated more like
"return" or more like "return <value>". So please do whatever can be
implemented easily.

--Guido van Rossum (home page: http://www.python.org/~guido/)

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