Implemented __eq__ function for Kovats and CubicSpline via ComputationMethod class

[hechth]

Implemented equality comparison in abstract base class based on class identity.

Fixes #50

[xtrojak]

Just a note to consider - if in the future you will possibly use nested inheritance
(e.g. create a new Computation Method XY from Kovats, where you, for example, change only one of its methods).

class XY(Kovats):
    ...

Then, this kind of equality check Kovats() == XY() returns True, because isinstance considers also inheritance. Is that desired behavior? (See this SO post for more detials)

A way to change this is to explicitelly compare their types, i.e.

def __eq__(self, o: object) -> bool:
        return type(o) == type(self)

[hechth]

Thanks for the comment! My linter complains about the type comparison with type(o) == type(self) and I am aware of the subclassing issue.

I don't think there will be computation methods derived from any of the derived classes, but this is good to know. I might violate the linter and change the type check to this one which seems to be stricter.

[martenson]

What is the linter's output?

[hechth]

Using type() instead of isinstance() for a typecheck.

[martenson]

It is unclear to me what is the intended use of this equality comparator. Could you please elaborate a bit @hechth?

[hechth]

It is unclear to me what is the intended use of this equality comparator. Could you please elaborate a bit @hechth?

The use is to be able to compare them using == in test cases. It would also be possible to move the chek to the test case and not implement the function I think.

[martenson]

The usage is unclear to me but it works fwiw. Be wary of what is actually being compared when using it though.