Why is Self assignable in Delphi?

Question

This code in a GUI application compiles and runs:

procedure TForm1.Button1Click(Sender: TObject);
begin
  Self := TForm1.Create(Owner);
end;

<

Answer 1

Sometimes, when you want to optimize a method for as far as you can take it (without resorting to assembly), 'Self' can be (ab)used as a 'free' variable - it could just mean the difference between using stack and using registers.

Sure, the contents of the stack are most probably already present in the CPU cache, so it should be fast to access, but registers are even faster still.

As a sidenote : I'm still missing the days when I was programming on the Amiga's Motorola 68000 and had the luxury of 16 data and 16 address registers.... I can't believe the world chose to go with the limited 4 registers of the 80x86 line of processors!

And as a final note, I choose to use Self sometimes, as the Delphi's optimizer is, well, not optimizing that well, actually. (At least, it pales compared to what trickery one can find in the various LLVM optimizers for example.) IMHO, and YMMV of course.