[Python-Dev] patch: try/finally in generators

[Oren Tirosh]

On Mon, Jul 29, 2002 at 03:40:01PM -0400, Guido van Rossum wrote:
> > > I'm not sure I understand what it does.  The return instruction at
> > > the end of the code, if I take this literally, isn't enclosed in
> > > any try/finally blocks.  So how can this have the desired effect?
> > 
> > They're on the block stack.  The stack unwind does the rest.
> 
> OK.  Your way to find the last return statement gives me the willies
> though. :-(

Yeah, I know. I'm not too proud of it but I was looking for instant 
gratification...

> Of course, since Jython has garbage collection, your finally clause
> may be executed later than you had expected it, or not at all!  Are
> you sure you want this?  

The same question applies to the __del__ method of any local variables 
inside the suspended generator.  I tend to rely on the reference counting
semantics of CPython in much of my code and I don't feel bad about it.

> There are a few other places that invoke Python code in a dealloc
> handler (__del__ invocations in classobject.c and typeobject.c).  They
> do a more complicated dance with the reference count.  Can you check
> that you are doing the right thing?

The __del__ method gets a reference to the object so it needs to be
revived.  Generators are much simpler because the generator function does 
not have any reference to the generator object.

	Oren