[Python-Dev] Garbage collecting closures (original) (raw)

Phillip J. Eby pje@telecommunity.com
Mon, 14 Apr 2003 12:08:38 -0400

At 11:58 AM 4/14/03 -0400, Jeremy Hylton wrote:

On Mon, 2003-04-14 at 11:52, Phillip J. Eby wrote: > If I understand correctly, it should also be breakable by deleting 'foo' > from the outer function when you're done with it. E.g.: > > def bar(a): > def foo(): > return None > x = a > foo() > > del foo # clears the cell and breaks the cycle >

You haven't tried this, have you? ;-)

Well, I did say, "If I understand correctly". :)

What's funny is, I could've sworn I've used 'del' under similar circumstances before. It must not have been to delete a cell, just deleting something else in a function that defined a function. Ah well.

SyntaxError: can not delete variable 'foo' referenced in nested scope

Interestingly, it gives me a different error in IDLE: "unsupported operand type(s) for -: 'NoneType' and 'int'"

Since foo() could escape bar, i.e. become reachable outside of bar(), we don't allow you to unbind foo.

So do this instead:

foo = None