[Python-Dev] 2.5 and beyond

[Greg Ewing]

Giovanni Bajo wrote:

>>>>a = []
>>>>for i in range(10):
> 
> ...     a.append(lambda: i)
> ...
> 
>>>>print [x() for x in a]
> 
> [9, 9, 9, 9, 9, 9, 9, 9, 9, 9]
> 
> This subtle semantic of lambda is quite confusing, and still forces people to
> use the "i=i" trick.

This has *nothing* to do with the semantics of lambda!
It's because Python's for-loop doesn't put its control
variable in a new scope, the way Scheme's equivalent
construct does.

*That's* what needs to be addressed to fix this problem.
I've made a suggestion about that before, but Guido
rejected it, so I won't repeat it here.

--
Greg