[fpc-pascal] Generic type conflicts

[Ryan Joseph]

I've wanted to make a generic version of a vector for a while but I always give up because it seems not very possible. It's probably not even a great idea because many methods don't translate between float and integer but I wanted to prevent other code duplication if possible.

Here's an example of how things break down. Are there any solutions for this currently? I feel like generics need to support some compiler directives so different blocks of code can specialize different depending on the type.

{$mode objfpc}
{$modeswitch advancedrecords}

program generic_vector_2;
uses
  Math;

type
  generic TVec2<TScalar> = record
    x, y: TScalar;
    function Normalize: TVec2;
  end;
  TVec2f = specialize TVec2<Float>;
  TVec2i = specialize TVec2<Integer>;

function TVec2.Normalize: TVec2;
var
  fac: TScalar;
begin
  // Can't determine which overloaded function to call
  // Incompatible types: got "Extended" expected "LongInt"
  fac:=Sqrt(Sqr(x) + Sqr(y));
  if fac<>0.0 then begin
    // Incompatible types: got "Single" expected "LongInt"
    fac:=1.0/fac;
    result.x:=x*fac;
    result.y:=y*fac;
  end else begin
    result.x:=0;
    result.y:=0;
  end;
end;

begin
end.

Regards,
	Ryan Joseph