Chris Rebert
On Tue, Oct 18, 2011 at 7:14 PM, Nikolaus Rath
wrote: Hello,
I often have code of the form:
def my_fun(): allocate_res1() try: # do stuff allocate_res2() try: # do stuff allocate_res3() try: # do stuff finally: cleanup_res3() finally: cleanup_res2() finally: cleanup_res1()
return
With increasing number of managed resources, the indentation becomes really annoying, there is lots of line noise, and I don't like the fact that the cleanup is so far away from the allocation.
Use the `with` statement and context managers. They were added for this exact situation. See http://www.python.org/dev/peps/pep-0343/
Resulting code will resemble:
def func(): with alloc() as res1, alloc() as res2, alloc() as res3: # do stuff
I think they're not for exactly this situation for two reasons: 1. This requires the alloc() functions to be context managers. If they're not, then I need to code a wrapping context manager as well. It's probably possible to write a generic wrapper that works for any cleanup function, but the result is not going to look very nice. 2. If I don't want to allocate the resources all at the same time, the indentation mess is still the same: def func(): with alloc() as res1: # do stuff with alloc() as res2: # do stuff with alloc() as res3: # do stuff Best, -Nikolaus -- »Time flies like an arrow, fruit flies like a Banana.« PGP fingerprint: 5B93 61F8 4EA2 E279 ABF6 02CF A9AD B7F8 AE4E 425C