delphi - 使用部分委托(delegate)实现接口(interface)

Question

我有一个只实现部分接口(interface)的子对象:

  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;

我想知道是否有有效的映射语法 TMyTest.P2至 FMyTestP2Impl.P2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

您必须使用 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;