[Python-ideas] 'Injecting' objects as function-local constants

[Jan Kaliszewski]

Nick Coghlan dixit (2011-06-13, 21:57):

>     def do_and_remember(val, verbose=False):
>           @def mem=collections.Counter()
>           result = do_something(val)
>           mem[val] += 1
>           if verbose:
>               print('Done {} times for {!r}'.format(_mem[val], val))
> 
> The @def ("at def") statement is just a new flavour of the same
> proposal that has been made many times before: a way to indicate that
> a simple assignment statement should be executed once at function
> definition time rather than repeatedly on every call to the function.

If using '@' character, I'd rather prefer:

    @in(mem=collections.Counter())
    def do_and_remember(val, verbose=False):
        result = do_something(val)
        mem[val] += 1
        if verbose:
            print('Done {} times for {!r}'.format(_mem[val], val))

@in (or @with, or @within, or @withlocal, or...) could be a language
syntax construct, not a real decorator, though using -- already well
settled -- decorator-like syntax. Important advantage of this variant is
IMHO that then it is obvious for everybody that the binding(s) is (are)
being done *early*.

Regards.
*j