Use decorator module for signature-preserving decorators

[OOPMan]

It looks like your awesome cached and multi_cached decorators don't make use of https://pypi.python.org/pypi/decorator which helpers write cleaner decorators that benefit from signature-preservation (which is important to some people :-)

I could submit a PR if you like?

[argaen]

Hi @OOPMan, do you have an example use case, if possible I would prefer to use https://docs.python.org/3/library/functools.html#functools.wraps rather than adding a new dependency :)

[OOPMan]

@argaen I believe you can achieve the same with wraps (In fact, I think decorator does use wrap to some extent) but there's more work involved.

Honestly, I wouldn't consider this a high priority, it's just something I've run into now and then with certain code trying to implement the concept of interfaces in Python and checking that functions conform to the interface (IIRC, this is a thing in the Zope part of the Python world). When you decorate such a function in a non-signature preserving way the interface nonsense complains because a function which was a(b,c,d,e) is now a(*args, **kwargs)

It's really rather silly :-)

[argaen]

I'm happy to add the functools.wraps part. Once I have the MR I can ping you to see if there is anything you are missing :)

[OOPMan]

@argaen Sure