Перегрузка операций

type 
  Frac = record
  private
    num,denom: integer;
  public  
    constructor (n,d: integer);
    begin
      num := n;
      denom := d;
    end;
    class function operator+(a,b: Frac): Frac; 
    begin
      Result := new Frac(a.num*b.denom+b.num*a.denom,a.denom*b.denom); 
    end; 
    function ToString: string; override;
    begin
      Result := Format('{0}/{1}',num,denom);
    end;
  end;
 
var 
  f := new Frac(1,2);
  f1 := new Frac(3,5);
 
begin
  writelnFormat('{0} + {1} = {2}',f,f1,f+f1);
end.