[Python-ideas] Allow accessing return value inside finally clause

[Georg Brandl]

On 12/25/2012 10:46 PM, Ram Rachum wrote:
> Say I have this function:
> 
>     def f():
>         try:
>             return whatever()
>         finally:
>             pass # I want to get what `whatever()` returned in here
> 
> I want to get the return value from inside the `finally` clause.
> 
> I understand that this is currently not possible. I'd like that to be possible
> because that would allow post-processing of a function's return value.
>
> What do you think?

Please supply a more complete example of what you are trying to achieve.

As it is, I wonder what your motivation is for using a "finally", because
in the case of an exception, there won't even *be* a return value to
postprocess.

If you're trying to use try-finally as a sort of nonlocal exit mechanism (like
the famous "goto done" in CPython sources), you probably would be fine with

ret = None
try:
    if x:
        ret = blah
        return
    # more cases with returns here
finally:
    # post-process ret here
    return ret

But I would consider this an abuse of try-finally, especially since it
suppresses proper propagation of exceptions.

cheers,
Georg