[Python-ideas] with-statement syntactic quirk

[Yuval Greenfield]

On Sun, Nov 4, 2012 at 5:41 PM, Nick Coghlan <ncoghlan at gmail.com> wrote:

> Yep. You can also do some pretty interesting things with ExitStack
> because of the pop_all() operation (which moves all of the registered
> operations to a *new* ExitStack instance).
>
> I wrote up a few of the motivating use cases as examples and recipes
> in the 3.3 docs:
> http://docs.python.org/3/library/contextlib#examples-and-recipes
>
> I hope to see more interesting uses over time as more people explore
> the possibilities of a dynamic tool for composing context managers
> without needing to worry about the messy details of unwinding them
> correctly (ExitStack.__exit__ is by far the most complicated aspect of
> the implementation).
>
> Cheers,
> Nick.
>
>
Pretty interesting things indeed. It does look like the concept is very
powerful. If I were to design a language I might have just given every
function an optional ExitStack. I.e. an explicit, dynamic, introspectable
version of defer.
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