Re: operators pow and **

14 Dec 2000

      Frank Heckenbach a Ã©crit :
...
Maurice Lombardi wrote:

...
...
It seems that operators pow and ** cannot be redefined in gpc. Is that expected ?
No, they should be. I think adding them in
parse.y:operator_identifier should do the trick, but there's a
comment stating exactly that this "is unnecessary". Seems it is
necessary, but since I don't know the real meaning of this comment,
I'll leave this to Peter... (maur7.pas)
With today snapshot (20001214) pow and shl work as expected, but ** compiles but fails when using it
with a message:

operatordemo.pas: In function `pascal_main_program':
operatordemo.pas:49: left operand of `**' must be of integer, real or complex type

The test program is just an expansion of operatordemo:

------------------------------------------------------
program OperatorDemo;

type
  Vector3 = record
    x, y, z: Real;
  end;

var
  a, b, c: Vector3 = (1, 2, 3);

operator + (u, v: Vector3) w: Vector3;
begin
  w.x := u.x + v.x;
  w.y := u.y + v.y;
  w.z := u.z + v.z;
end;

operator pow (u: Vector3; v: integer) w: Vector3;
begin
  w.x := u.x pow v;
  w.y := u.y pow v;
  w.z := u.z pow v;
end;

operator shl (u: Vector3; v:integer) w: Vector3;
begin
  w.x := round(u.x) shl v;
  w.y := round(u.y) shl v;
  w.z := round(u.z) shl v;
end;

operator ** (u: Vector3; v:real) w: Vector3;
begin
  w.x := u.x ** v;
  w.y := u.y ** v;
  w.z := u.z ** v;
end;

begin
  c := a + b ;
  writeln(c.x,'  ',c.y,'  ',c.z);

  c := a pow 3;
  writeln(c.x,'  ',c.y,'  ',c.z);

  c := a shl 2;
  writeln(c.x,'  ',c.y,'  ',c.z);

  c := a ** 2.5;                     (* WRONG *)
  writeln(c.x,'  ',c.y,'  ',c.z);

  readln;

end.
------------------------------------------------

Hope this helps

Maurice

-- 
       Maurice Lombardi
Laboratoire de  Spectrometrie Physique,
Universite Joseph Fourier de Grenoble, BP87
38402 Saint Martin d'Heres Cedex     FRANCE
Tel: 33 (0)4 76 51 47 51
Fax: 33 (0)4 76 51 45 44
mailto:Maurice.Lombardi@ujf-grenoble.fr