threading support in python

[Steve Holden]

sjdevnull at yahoo.com wrote:
> Paul Rubin wrote:
> 
>>Jean-Paul Calderone <exarkun at divmod.com> writes:
>>
>>>>which more explicitly shows the semantics actually desired.  Not that
>>>>"huge" a benefit as far as I can tell.  Lisp programmers have gotten
>>>>along fine without it for 40+ years...
>>>
>>>Uh yea.  No lisp programmer has ever written a with-* function... ever.
>>
>>The context was Lisp programmers have gotten along fine without
>>counting on the refcounting GC semantics that sjdevnull advocates
>>Python stay with.  GC is supposed to make it look like every object
>>stays around forever, and any finalizer that causes an explicit
>>internal state change in an extant object (like closing a file or
>>socket) is not in the GC spirit to begin with.
> 
> 
> I disagree, strongly.  If you want "every object stays around forever"
> semantics, you can just not free anything.  GC is actually supposed to
> free things that are unreachable at least when memory becomes tight,
> and nearly every useful garbage collected language allows destructors
> that could have effects visible to the rest of the program.  Reference
> counting allows more deterministic semantics that can eliminate
> repeating scope information multiple times.
> 
Clearly you guys are determined to disagree. It seemed obvious to me 
that Paul's reference to making it "look like every object stays around 
forever" doesn't exclude their being garbage-collected once the program 
no longer contains any reference to them.

You simplify the problems involved with GC-triggered destructors to the 
point of triviality. There are exceedingly subtle and difficult issues 
here: read some of the posts to the python-dev list about such issues 
and then see if you still feel the same way.

regards
  Steve
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