[Python-ideas] Yield-From: Finalization guarantees
jh at improva.dk
Mon Mar 30 00:21:19 CEST 2009
Nick Coghlan wrote:
> Jacob Holm wrote:
>> The problem is that any exception thrown into inner is converted to a
>> GeneratorReturn, which is then swallowed by the yield-from instead of
>> being reraised.
> That actually only happens if inner *catches and suppresses* the thrown
> in exception.
Having a return in the finally clause like in my example is sufficient
to suppress the exception.
> Otherwise throw() will reraise the original exception
I am not sure what your point is. Yes, this is a corner case. I am
trying to make sure we have the corner cases working as well.
In the example I gave I think it was pretty clear what should happen
according to the inlining principle. The suppression of the initial
exception is an accidental side effect of the refactoring. It looks to
me like using the __cause__ attribute on the GeneratorReturn will allow
us to reraise the exception. This seems like exactly the kind of thing
that the __cause__ and __context__ attributes from PEP 3134 was designed
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