[fpc-pascal] generics class hierarchy

[David Emerson]

Sven Barth wrote:
> I've now looked at your example code in more detail (I was working the 
> last time I wrote you). Where did you define "_t_point"? I only found a 
> "t_point" in your second mail.

_t_point is part of the template list.

I guess it's a limitation. Conceptually it doesn't seem that different to be 
specifying a class to inherit from in the template list, but the compiler isn't 
handling it yet.

> Would you please post (or at least attach) your complete test unit? In 
> the meantime I'll try to test it with the code pieces you wrote.

unit genericstest;

{$mode objfpc}

interface

uses
  classes,
  sysutils;

type
  generic gt_point <_num> = class
    f_left, f_top : _num;
    procedure set_lt (l, t : _num); virtual;
    end;

type
  generic gt_box<_t_point,_num> = class (_t_point)   // FAILS :-(
    f_width, f_height : _num;
    end;

  t_real_point = specialize gt_point<single>;

  t_special_real_point = class (t_real_point)
    procedure set_lt (l, t : single); override;
    end;

implementation

procedure gt_point.set_lt (l, t : _num);
  begin
    f_left := l;
    f_top := t;
  end;

procedure t_special_real_point.set_lt (l, t : single);
  begin
    inherited;
  end;

end.