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python decorator

Ian Kelly ian.g.kelly at gmail.com
Wed Feb 22 12:45:31 EST 2017 
On Wed, Feb 22, 2017 at 8:16 AM, Pavol Lisy <pavol.lisy at gmail.com> wrote:
> Maybe this technique could be reusable (and maybe part of functools?)
>
> With this decorator:
>
>     def wrap_args(decorator):
>         def decor_out(*args, **kwargs):
>             def decor_in(func):
>                 return decorator(func, *args, **kwargs)
>             return decor_in
>         return decor_out
>
> Alfredo needs to change only (*) next 2 lines:
>
>     def fun_cache(function):
>         memo = {}
>
> to:
>
>     @wrap_args
>     def fun_cache(function, cache):
>         memo = cache
>
> (*) - Steve's improvements (for example using functools.wraps) are
> good to consider as well! :)
> (but maybe catching TypeError could more problems hide than solve)

When all the arguments are optional it's generally desirable that @foo
and @foo() be equivalent. See:

https://blogs.it.ox.ac.uk/inapickle/2012/01/05/python-decorators-with-optional-arguments/

I would augment that example by making the optional arguments
keyword-only to prevent accidentally passing one as the function to be
decorated. Hopefully this feature would also be part of any general
reusable solution.
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