[Python-ideas] Avoiding nested for try..finally: atexit for functions?

[Paul Moore]

On 19 October 2011 14:54, Nikolaus Rath <Nikolaus at rath.org> wrote:
>> The "with" statement is a good answer.  If for some reason you need to
>> be compatible with version of Python so old it doesn't have it, then try
>> the bzrlib.cleanup module in bzr.  It implements the sort of API you
>> describe above.
>
> Yes, that's sort of what I was thinking about. I think the API is still
> more convoluted than necessary, but that's probably because it works
> with Python 2.4.
>
> Having thought about this a bit more, I think it should be possible to
> use 'with' rather than decorators to implement something like this:
>
> with CleanupManager() as mngr:
>     allocate_res1()
>     mngr.register(cleanup_res1)
>     # do stuff
>     allocate_res2()
>     mngr.register(cleanup_res2)
>     # do stuff
>     allocate_res3()
>     mngr.register(cleanup_res3)
>     # do stuff
>
> The mngr object would just run all the registered functions when the
> block is exited.

That's probably better than my decorator suggestion, because it allows
you to limit the scope precisely, rather than just being
function-scope. The CleanupManager class might make a good addition to
contextlib, in actual fact...

Paul.