@lru_cache on functions with no arguments

[Serhiy Storchaka]

03.08.17 18:36, Ian Kelly пише:
> The single variable is only a dict lookup if it's a global. Locals and
> closures are faster.
> 
> def simple_cache(function):
>      sentinel = object()
>      cached = sentinel
> 
>      @functools.wraps(function)
>      def wrapper(*args, **kwargs):
>          nonlocal cached
>          if args or kwargs:
>              return function(*args, **kwargs)  # No caching with args
>          if cached is sentinel:
>              cached = function()
>          return cached
>      return wrapper
> 
> *Zero* dict lookups at call-time. If that's not (marginally) faster
> than lru_cache with maxsize=None I'll eat my socks.

With salt?

$ ./python -m timeit -s 'from simple_cache import simple_cache; f = 
simple_cache(int)' -- 'f()'
500000 loops, best of 5: 885 nsec per loop
$ ./python -m timeit -s 'from functools import lru_cache; f = 
lru_cache(maxsize=None)(int)' -- 'f()'
1000000 loops, best of 5: 220 nsec per loop