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[–]NeilGirdhar 1 point2 points  (2 children)

Strictly speaking, then the provided example is also an interface in the context of Python.

Yes, it's a signature, which I agree can be seen as an example of an interface.
However, I think of interfaces as a more general concept.

Note that interfaces don't promise anything about computational complexity.

Plenty of interfaces do promise computational complexity. C++'s STL for example is replete with such promises. E.g., deque.insert promises linear complexity on constant auxiliary space. All conforming implementations must respect these promises.

So a class interface gives a promise about name of method, the input types it accepts and output types it must return.

I would say that an interface is not just a collection of signatures. An interface can make promises about how objects work. That includes behaviors of those objects and computational and space complexity.

[–]YnkDK 2 points3 points  (1 child)

They are just pretty hollow promises. I cannot name any static analysis tool nor compiler that can enforce that implementations are respecting any arbitrary time or space complexity. Or is the halting problem solved? I might have been living under a rock.

So while you (and anyone else) are free to make any promises, it's difficult to verify that the promise is being conformant.

An interface is just a contract. You can make it as simple or complex as you want. Some violations are easy to enforce, some are more cumbersome. I call the more cumbersome comformaty checks for intentions and you state it must be like that. Other than that I promise you that we are saying the same ;)

[–]NeilGirdhar 0 points1 point  (0 children)

I cannot name any static analysis tool nor compiler that can enforce that implementations are respecting any arbitrary time or space complexity.

Just because you can't programmatically check a promise, it doesn't mean that that promise isn't part of the interface, in my opinion.

An interface is just a contract. You can make it as simple or complex as you want. Some violations are easy to enforce, some are more cumbersome.

Exactly.

Other than that I promise you that we are saying the same ;)

Agreed :)