Parent references: hot or not?

[Andrew Bennetts]

On Sat, Apr 19, 2003 at 10:07:41AM -0700, Dylan Reinhardt wrote:
> On Sat, 2003-04-19 at 10:00, Dylan Reinhardt wrote:
> 
> > Sounds like I should be sure to write a __del__ method for Container
> > that ensures things work correctly.
> 
> And upon re-reading your post you say *not* to do that... :-)
> 
> I'd like to understand that a bit better.  What would be wrong with:
> 
> class Container:
> 
>    def __del__(self):
>       # ensure all Items are deleted first
>       for item in self.items.keys():
>          del self.items[item]

Calling self.items.clear() would be simpler than looping.

But it's redundant.  The garbage collector will collect cycles for you
automatically, so don't waste your time doing unnecessary house-keeping --
particularly because if you *do* define __del__, but somehow accidentally
end out with that object in a reference cycle anyway, it can't be collected.
See http://python.org/doc/current/lib/module-gc.html#l2h-312 for a brief
explanation.  

There are very few reasons to define __del__ in modern versions of Python.

-Andrew.