[1718627440]

This is one interpretation. The other is that the interface of check_flags() specifies, that any implementation of it is only allowed to differ on the type of the object and not any other property.

You already prescribe with the chosen arguments in the superclass on which things the child implementation can depend. Why not also do this with the first argument?

[ryao]

You would typically put the this pointer into the first argument when doing OOP in C. You can put the this pointer in the last argument to have it work too. However, you cannot omit it entirely. That is something that is not OOP. It is an ADT.

[1718627440]

So suppose you have it, but never use it. Then why have it you can just remove the first parameter. You can have object methods in C++ too, that don't use the this pointer.

Also why do you care exactly about the order of arguments? The nature of the function doesn't change, it's entirely arbitrary and orthogonal to the paradigm the function implements. Another example is the implementation of the equality operator between objects. In languages with syntactic sugar you typically have (self, other), but if its the true equality operator then the order doesn't matter.