Hacker News new | ask | show | jobs
by 1718627440 300 days 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.
1 comments
ryao 300 days ago
Read the definition again. The programming language here is not the one using this. It is the programmer using it.
link
1718627440 299 days ago
Which means that it's not the language doing OOP, but the programmer.
link
ryao 299 days ago
The 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.
link
1718627440 299 days ago
Ok, 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.
link
ryao 299 days ago
It 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.
link
1718627440 299 days 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.

link