[Python-Dev] New PEP: 319

2003年6月16日 10:22:17 +0400 (MSD)

On 2003年6月16日, Michel Pelletier wrote:
> def __init__(self):
> self.counter = 0
>> def increment(self):
> synchronize:
> self.counter += 1

What about just adding a parameter to try operator?
 def increment(self):
 try self.counter_lock:
 self.counter += 1
- this will save from keyword and could also be used with
except part with, for example, se-syncronization outcomes
for some kinds of locks:
 def increment(self):
 try self.counter_lock:
 self.counter += 1
 except SomeLockError:
 bla-bla-bla
 
> Is your question, What is the unqualified lock associated with, the
> instance, the class, the method, the counter, or something else? If it is
> your question then the answer is I'm not sure now that I've thought about
> it deeper. Clearly the concept of the synchronization is around the
> counter, although now I can see no way to associate that implicitly. 
> Perhaps this is why Java does not have unqualified synchronized blocks and
> maybe I should remove it in which case the previous code would be:
>> class SynchronizedCounter:
>> def __init__(self):
> self.counter = 0
>> def increment(self):
> synchronize self.counter:
> self.counter += 1
>> > I'd also like to see how 'asynchronize' works with condition
> > variables, which seem to be the most common use for temporarily
> > unlocking.
>> I will look into that.
>> > (Your example of how code would do this without
> > asynchronize has a bug, by the way; if the I/O operation raises an
> > exception, the finally clause will attempt to release an already
> > released lock.)
>> Yes I need another try/finally in there. Thanks.
>> > I think the PEP would be clearer if it was considerably shorter and to
> > the point, with fewer examples and a more exact specification.
>> Thanks for the advice, I will move my thinking in this direction.
>> -Michel
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Sincerely yours, Roman A.Suzi
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