[Python-Dev] With statement (original) (raw)

John Williams jrw@pobox.com
Wed, 05 Feb 2003 11:00:37 -0600

Michael Hudson wrote:

Oren Tirosh <oren-py-d@hishome.net> writes:

Let's assume that a new 'local' statement is added to Python. At the end of the current block the del method of any references declared local is guaranteed to be called. [snip] Two comments: 1) The resource-allocation-is-initialization pattern works very well in C++, but I'm unconvinced that we should aim to copy it exactly -- it's a nice solution to the problem, but not the only possible or best one, IMHO. 2) Without the ability to define a scope at will, RAiI becomes less useful.

Why not combine the "with" and "local" statement ideas? Change the "with" statement so that there is no enter method, and call del where there current proposal calls exit. Now you have

with f = file(...): # Do something with f.

meaning something similar to

f = file(...) try: # Do something with f. finally: assert sys.getrefcount(f) == 2 del f # f is guaranteed dead, so f.del is called