more flexible cached_member decorator

[jonasleitner]

There are 2 problems with the current version (see example below):

• It is not possible to call a decorated function with keyword arguments (quality of life)
• The decorator does not work with default arguments and might unexpectedly not load results from the cache.

Neither of the points is currently a problem. Just to have it sorted for the future.
The new version should either work as intended (including the 2 points listed above) or raise an exception if a member function can't be wrapped with the decorator.

from adcc.misc import cached_member_function

class Test:
    @cached_member_function
    def foo(self, x, y = 1):
        print(x, y)

t = Test()

# this will not work
t.foo(x=2)

# this will print twice because the default argument
# is not correctly considered
t.foo(0)  # key for cache lookup: (0,)
t.foo(0, 1)  # key for cache lookup: (0, 1)

[jonasleitner]

@apapapostolou @maxscheurer can one of you take a quick look?
Since I'm using this code snippet in the equation generator I am pretty sure everything should work.

[maxscheurer]

I'm gonna play the bad guy 😂
Can you please add a unit test that tests the functionality and failures of the edge cases, e.g. kwarg only etc? Just a suggestion...

[jonasleitner]

Should have seen that one coming 😂👌
I think this should cover most cases. Did I miss something?