Python 3 removes name binding from outer scope

[Steven D'Aprano]

On Tue, 25 Jul 2017 17:02:48 +1000, Ben Finney wrote:

> Ben Finney <ben+python at benfinney.id.au> writes:
> 
>> Having to make another name for the same object, merely to avoid some
>> surprising behaviour, is IMO un-Pythonic.
> 
> I suppose my objection is rooted in the fact this behaviour is implicit;
> my code has not issued a ‘del’ statement, and so I don't expect one; yet
> it occurs implicitly. This violates the Zen of Python.


Technically, *all* garbage collection is implicit. You don't have to 
explicitly delete your local variables when you return from a function, 
they are implicitly deleted when they go out of scope.

So consider this as a de-facto "the except clause "as name" variable is 
treated *as if* it exists in its own scope.

I agree that the behaviour of except is a little surprising, but that's 
(according to the core devs) the lesser of two evils. The alternative is 
a memory leak when the traceback keeps data alive that you didn't expect.



-- 
“You are deluded if you think software engineers who can't write 
operating systems or applications without security holes, can write 
virtualization layers without security holes.” —Theo de Raadt