[Python-Dev] Proposed addition to threading module (original) (raw)

Guido van Rossum guido at python.org
Tue Apr 25 01:56:54 CEST 2006

On 4/24/06, "Martin v. Löwis" <martin at v.loewis.de> wrote:

Tim Peters wrote: > Does > > with cv: > > work to replace the outer (== only) acquire/try/finally/release dance?

Indeed it does - although implemented in a somewhat convoluted way: A lock is a context (or is that "context manager"), i.e. it implements def context(self): return self enter=acquire def exit(self,*args): return self.release() #roughly A Condition has a lock, so it could become the context (manager?) through def context(self): return self.lock However, instead of doing that, it does def context(self): return self # roughly: enter is actually set in init to self.lock.acquire def enter(self): return self.acquire() def exit(self): return self.release Looks somewhat redundant to me, but correct.

Thanks -- I didn't see the shortcut when I coded this. I'll fix it.

Tim is right, the UNLOCK/LOCK part is implied in the wait() call. However, the wait() implementation really does provide a use case for the primitive operation that Nick proposed, and it can't be refactored to remove the pattern Martin disapproves of (though of course the existing try/finally is fine). I'm not sure if the use case is strong enough to warrant adding it; I think it's fine not to support it directly.

-- --Guido van Rossum (home page: http://www.python.org/~guido/)

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