[Python-ideas] Tweaking closures and lexical scoping to include the function being defined

[Jan Kaliszewski]

Nick Coghlan dixit (2011-09-28, 05:59):

>     def accumulator():
>         def incr(x) [tally=0]:
>             tally += x
>             return tally
>         return incr
> 
> As the rough equivalent of today's:
> 
>     def accumulator():
>         tally = 0
>         def incr(x):
>             nonlocal tally
>             tally += x
>             return tally
>         return incr

IMHO such a syntax (or a special or non-special decorator) should simply
allow to add free variable(s) to a function. Then, if we want to modify
such a variable in the function body we should use nonlocal, as with
today's closures:

    def accumulator():
        def incr(x) [tally=0]:
            nonlocal tally
            tally += x
            return tally
        return incr

But we would not need to use nonlocal for read-only access, as with
today's closures:

    def my_func() [lock=Lock()]:
        with lock:
            "foo"

Cheers.
*j