IfThen<T>をrecordで実装する

Implement IfThen by generics and advanced record

type
  &IF = record
    class function &Then<T>(AValue: Boolean; AThen: T; AElse: T): T; static; inline;
  end;

class function &IF.&Then<T>(AValue: Boolean; AThen: T; AElse: T): T;
begin
  if AValue then
  begin
    Result := AThen;
  end
  else
  begin
    Result := AElse;
  end;
end;

var
  I: Integer;
  D: Double;
  S: String;
  B: TButton;
begin
  I := &IF.&Then(False,1,2);
  D := &IF.&Then(True,1.0,2.0);
  S := &IF.&Then(False,'OK','NG');
  B := &IF.&Then(Button1.Enabled,Button1,Button2);
end;