Home / Questions / 22069
Accepted
jachguate
Asked: 2020-08-31 06:27:59 +0800 CST 2020-08-31 06:27:59 +0800 CST

Does calling overloaded functions or methods incur a runtime cost?

  • 772

Are there any additional runtime costs for calling overloaded methods?

I'm asking this specifically for Delphi , in case the answer isn't the same for all compiled languages.

I think there should be no additional cost since it should be resolved at compile time, but you can never be sure, can you?

delphi

1 Answers

  1. Best Answer

    Of course you can be sure, because it is documented . It's resolved by the compiler (at compile time, of course), so there's no additional cost associated with calling overloaded functions or methods in Delphi.

    I've done a little experiment to prove it:

    var
  j: Integer;
  st: string;

procedure DoNothing(i: Integer); overload;
begin
  j := i;
end;

procedure DoNothing(s: string); overload;
begin
  st := s;
end;

procedure DoNothingI(i: integer);
begin
  j := i;
end;

procedure TForm2.Button1Click(Sender: TObject);
const
  MaxIterations = 10000000;
var
  StartTick, EndTick: Cardinal;
  I: Integer;
begin
  StartTick := GetTickCount;
  for I := 0 to MaxIterations - 1 do
    DoNothing(I);
  EndTick := GetTickCount;
  Label1.Caption := Format('Overlaod ellapsed ticks: %d [j:%d]', [EndTick - StartTick, j]);
  StartTick := GetTickCount;
  for I := 0 to MaxIterations - 1 do
    DoNothingI(I);
  EndTick := GetTickCount;
  Label1.Caption := Format('%s'#13'Normal ellapsed ticks: %d [j:%d]', [Label1.Caption, EndTick - StartTick, j]);
end;

    Result: Almost every time it takes 31 ticks (milliseconds) for both on my dev machine, some times it takes only 16 ticks .

    execution time of 31 ms.

    • 0