Handle function defaults correctly

Right now, if you call some with function without specifying a default parameter, cache remembers it as ‘parameter not set’. If you change this default value in function definition, and call again without specifying this parameter, cache will incorrectly return the function output for the old value. Also, if you sometimes use the default and sometimes specify the value, the function will be be computed two times, needlessly.

It can be easily fixed by replacing this code: https://github.com/shaypal5/cachier/blob/5b0bff9af3dbd251ae657e4f6f27f269de977768/cachier/pickle_core.py#L152 with:

bound = inspect.signature(function).bind(*args, **kwargs)
bound.apply_defaults()
key = tuple((k, value) for k, value in sorted(bound.arguments.items()))

If you want this improvement I can do a PR.

[filyp]

Ok, I opened a draft PR #50

[shaypal5]

Hey @fsondej !

Ok, I’ve set up an alternative free server on Atlas mongodb.com. All tests are now passing. You will only be able to test MongoDb core functionalities when opening a PR from your fork, as the credentials are set up on travis, and it will run all tests on a PR.

You can now continue with your good work! 😃