delphi - 在子类中使用自类型参数创建泛型类或接口(interface)

Question

我想创建一个可以子类化的类或接口(interface)，始终使用当前类实例作为方法参数...

这是一个解释我的问题的示例:

 type IArithmeticObject = interface(IInterface)
   procedure assign(ao : IArithmeticObject);
   procedure add(ao : IArithmeticObject);
   procedure remove(ao : IArithmeticObject);
   procedure multiply(ao : IArithmeticObject);
   procedure divide(ao : IArithmeticObject);
 end;

接口(interface)IArithmeticObject应该是起点，引用基本算术运算，子类可以声明为

 type TInteger = class(TInterfacedObject, IArithmeticObject)
   procedure assign(ao : TInteger);
   procedure add(ao : TInteger);
   procedure remove(ao : TInteger);
   procedure multiply(ao : TInteger);
   procedure divide(ao : TInteger);
 end;

ao 的参数类型为 TInteger 而不是 IArithmeticObject。

另一个想法是使用自引用泛型类型，例如:

  AMathObject = class;

  AMathObject<T : AMathObject, constructor> = class
    procedure assign(ao : T);virtual;abstract;
    procedure add(ao : T);virtual;abstract;
    procedure remove(ao : T);virtual;abstract;
    procedure multiply(ao : T);overload;virtual;abstract;
    procedure divide(ao : T);virtual;abstract;
  end;

但我无法找出正确的语法...

有人对这种可能性(或不可能性)有任何想法吗？

Answer 1

如果我理解正确，您可能想从通用接口(interface)派生您的类。

type
  IArithmeticObject<T> = interface
    procedure assign(ao: IArithmeticObject<T>);
    procedure add(ao: IArithmeticObject<T>);
    procedure remove(ao: IArithmeticObject<T>);
    procedure multiply(ao: IArithmeticObject<T>);
    procedure divide(ao: IArithmeticObject<T>);
  end;

  TInteger = class (TInterfacedObject, IArithmeticObject<TInteger>)
    procedure assign(ao: IArithmeticObject<TInteger>);
    procedure add(ao: IArithmeticObject<TInteger>);
    procedure remove(ao: IArithmeticObject<TInteger>);
    procedure multiply(ao: IArithmeticObject<TInteger>);
    procedure divide(ao: IArithmeticObject<TInteger>);
  end;

根据Stefan Glienke's comment编辑的答案:现在类的方法接受声明为对象或接口(interface)的参数。

var
  ao: IArithmeticObject<TInteger>;
begin
  ao := TInteger.Create;
  ao.multiply(ao);
end.