使用部分委托实现接口

Question

我有一个子对象只实现了接口的一部分：

  IMyTest = interface
    procedure P1;
    procedure P2;
  end;

  TMyTestP2Impl = class
    procedure P2;
  end;

  TMyTest = class(TInterfacedPersistent, IMyTest)
  private
    FMyTestP2Impl : TMyTestP2Impl;
  public
    constructor Create();
    destructor  Destroy(); override;
    procedure P1;
    procedure P2;
  end;

所以我必须写TMyTest.P2如下：

procedure TMyTest.P2;
begin
  FMyTestP2Impl.P2();
end;

我想知道是否存在将TMyTest.P2 映射到FMyTestP2Impl.P2 的有效语法，而无需编写TMyTest.P2 的实现。我的意思是这样的：

  TMyTest = class(TInterfacedPersistent, IMyTest)
  private
    FMyTestP2Impl : TMyTestP2Impl;
  public
    constructor Create();
    destructor  Destroy(); override;
    procedure P1;
    procedure P2 = FMyTestP2Impl.P2;
  end;

Answer 1

你必须使用delegation to a class type property:

type
  IMyTest = interface
    procedure P1;
    procedure P2;
  end;

  TMyTestP2Impl = class
    procedure P2;
  end;

  TMyTest = class(TInterfacedPersistent, IMyTest)
  private
    FMyTestP2Impl: TMyTestP2Impl;
    property MyTestP2Impl: TMyTestP2Impl read FMyTestP2Impl implements IMyTest;
  public
    constructor Create;
    destructor  Destroy; override;
    procedure P1;
  end;