Memoization and encapsulation

[bonono at gmail.com]

Steven D'Aprano wrote:
> I was playing around with simple memoization and came up with something
> like this:
>
> _cache = {}
> def func(x):
>     global _cache
>     if _cache.has_key(x):
>         return _cache[x]
>     else:
>         result = x+1  # or a time consuming calculation...
>         _cache[x] = result
>         return result
>
> when it hit me if I could somehow bind the cache to the function, I could
> get rid of that pesky global variable.
>
what would be the problem of the following, other than exposing the
cache which the caller may override ?

def func(x,_cache={}):