[Python-ideas] Yield-From: Finalization guarantees

[Jacob Holm]

Nick Coghlan wrote:
> Jacob Holm wrote:
>   
>> Having a return in the finally clause like in my example is sufficient
>> to suppress the exception.
>>     
>
> Ah, I did miss that - I think it just means the code has been refactored
> incorrectly though.
>
>   
Ok

> I think the refactoring is buggy, because it has changed the code from
> leaving exceptions alone to suppressing them. Consider what it would
> mean to do the same refactoring with normal functions:
>
> def inner():
>    try:
>        perform_operation()
>    finally:
>        return 'VALUE'
>
> def outer():
>    val = inner()
>    print val
>
> That code does NOT do the same thing as:
>
> def outer():
>    try:
>        perform_operation()
>    finally:
>        val = 'VALUE'
>    print val
>   
Good point.  Based on this observation, I withdraw the proposal about 
storing the active exception on the GeneratorReturn and reraising it in 
yield-from.  I still think we should get rid of the check for 
GeneratorExit, because of the other example I gave.

- Jacob