[Python-ideas] Using functools.lru_cache only on some arguments of a function

[Michael Selik]

On Sat, Dec 5, 2015 at 6:11 PM Serhiy Storchaka <storchaka at gmail.com> wrote:

> On 04.12.15 23:44, Bill Winslow wrote:
> > def deterministic_recursive_calculation(input, partial_state=None):
> >      condition = do_some_calculations(input)
> >      if condition:
> >          return deterministic_recursive_calculation(reduced_input,
> > some_state)
> >
> > I want to memoize this function for obvious reasons, but I need the
> > lru_cache to ignore the partial_state argument, for its value does not
> > affect the output, only the computation expense.
>
> Memoize a closure.
>
> def deterministic_calculation(input):
>      some_state = ...
>      @lru_cache()
>      def recursive_calculation(input):
>          nonlocal some_state
>          ...
>          return recursive_calculation(reduced_input)
>      return recursive_calculation(input)
>

This would provide the dynamic programming aspect for the recursion, but
not cache across successive calls to the outer function. It does look
cleaner than the OO version.
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