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You can take the API for a linked list and implement a balanced binary search tree behind it, but continuing to call it a linked list after doing that is wrong.
by ryao 1y ago
You can take the API for a linked list and implement a balanced binary search tree behind it, but continuing to call it a linked list after doing that is wrong. Similarly, you can do pointer indirections the same way a vtable would do them, but if the things you get are not the equivalent of member function pointers, it is not a vtable.
- 1718627440 1y ago> In computer programming, a virtual method table (VMT), virtual function table, virtual call table, dispatch table, vtable, or vftable is a mechanism used in a programming language to support dynamic dispatch (or run-time method binding). (Wikipedia) When its a table of function pointers used for dynamic dispatch, to me it's a vtable. I don't care about their type signatures as long as they logically belong to the object in question. You seem to have a different very narrow definition of vtables, so the discussion is kind of useless.
- ryao 1y agoRead the definition again. The programming language here is not the one using this. It is the programmer using it.
- 1718627440 1y agoWhich means that it's not the language doing OOP, but the programmer.
- ryao 1y agoThe definition you quoted requires the language to be the one doing it for it to be a vtable. If the programmer is doing it, then it is not a vtable by that definition.
- 1718627440 1y agoOk, we can name it a vtable if it's done by the language and a wtable if it is done by the programmer. I don't care about this distinction, the mechanism is the same, the effects are the same, the implemented theory (OOP) is the same. Heck event the emitted code is the same. I guess the vtable implementations in a C++ compiler are now called wtables.
- ryao 1y agoIt is not the same theory, since it is an ADT, not anything object oriented. Different theories can and do overlap. The emitted code is also not the same, since there is no implicit this pointer. You are the one who posted a definition you found and then claimed that it agreed with you, when it did not and now are reneging on your use of it. You do not understand this topic as well as you think you do and this is a silly hill to die on.
- 1718627440 1y ago> You are the one who posted a definition you found and then claimed that it agreed with you X is Y used in Z. Does that mean X is not Y when it is not used in Z? A knife is a sharp object used to cut meat. How do I call the thing to cut fish? Yes, I see how you can parse the definition your way, I didn't thought about that before introducing it. > since it is an ADT, not anything object oriented Yes, they have large overlap. To my understanding, the difference is, that OOP has inheritance and an ADT can be provided by the big god object. The latter I would refrain to call OOP, although it can be argued it still is. I think our real discussion here is, whether a function entry that doesn't take an argument of the object type precludes it being a vtable. To me it is as long as this function is supposed to be a method of a single object and not for all objects in general, i.e. a global function.
- ryao 1y agoThe point of a vtable is to implement virtual member functions that support inheritance and polymorphism without changing the base class implementations no matter what the child classes do. If you omit the this pointer, you cannot do inheritance that uses the this pointer in an override without changing the implementation of the parent to add the this pointer back, which would be like a tail wagging a dog. Thus, it is not a vtable. It is something similar, but different.