Am Di., 4. Dez. 2018, 04:06 hat Ryan Joseph
geschrieben:
Show quoted text 12 lines
Some questions about old-style objects.
1) How can you check if self is assigned? self refers to the struct itself
but if the object was allocated on the stack then how do we know self is a
pointer or not?
procedure TMyObject.Free;
begin
if self nil then
dispose(self,Destroy);
end;
The type of "Self" inside a object is always the same no matter if it's allocated on the stack or the heap.
Show quoted text 8 lines
2) Is there any TObject support in objects? I know there is a VMT table
for objects but I’m not sure if it’s structure is public in the RTL.
class function TMyObject.ClassName:string;
begin
result := PVmt(self)^.vClassName^;
end;
Objects don't have TObject-like functionality. There is a VMT record, but that is only available if there is at least one virtual method.
3) why are operator overloads not supported in objects? Is there a
technical reason for that?
Operator overloads inside records were added much later than support for global operator overloads and because of Delphi compatibility. Thus there was simply no need to add support for them.
In addition to that one would need to dereference object pointer variables to use the operators (though that one is true for records as well).
Regards,
Sven
