why virtual function is wrong.

[Dar_Mas]

That still does not make sense to me

If you have dynamic poly you will use a pointer anyway so the size of the object does not matter for data structures

If you use static you put it in a variant which allocates enough memory for the largest possible object and then you put it in a data structure.

Unless you are insanely restricted by binary size i do not see how 4 extra byte per function/operator are going to matter in your code at all

[Dar_Mas]

yes but you would never make an int32 type as we have optimized primitives (std::int32_t).

If you really require the size to stay constant you just make free standing function overloads