Expose `get` and `has` methods

[epayet]

This has been mentioned in a few issues (https://github.com/medikoo/memoizee/issues/45, https://github.com/medikoo/memoizee/issues/33, https://github.com/medikoo/memoizee/issues/51).

The goal is to expose get and has methods so that we easily have read access to the cache, depending on the arguments. Hopefully, the tests will demonstrate really well how this works.

I tried to match your coding style, I am happy to take any feedback. This would be really useful for my use case described here: https://github.com/medikoo/memoizee/issues/33#issuecomment-278046852

I know you're planning to do a major refactor soon, but in the meantime, I think that exposing those 2 new methods are costless and will be really useful to some people, me included :)

Many thanks.

[medikoo]

Thanks @epayet, at first glance looks good. I'm keen to take it but would prefer to give it a more careful look. If not today, I'll take care of this on Monday.

[epayet]

Sure @medikoo thanks for the quick response 👍

[epayet]

I gave it another go according to your requested changes. Can you have a look now and give your feedback?

I left a note on async on another comment, this is an interesting case that I hope will be solved in v1. In the meantime, if you're happy with this code, it would still be very helpful.

Thanks :)

[medikoo]

@epayet looks great, just check my comment towards null handling :)

[epayet]

I added the null check for _has :) And the build is green 👍

[medikoo]

Thank you, published with v0.4.4

[epayet]

Thanks I just checked, it works 👍