覆盖虚方法

unit Unit1;



interface



uses

  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

  Dialogs;



type

  TForm1 = class(TForm)

    procedure FormCreate(Sender: TObject);

  private

    { Private declarations }

  public

    { Public declarations }

  end;



//夫类

  TParent = class

  protected

    function MyFun(i: Integer): Integer; dynamic;  //动态方法

    procedure MyProc; virtual;  //虚方法

  end;



//子类

  TChild = class(TParent)

  protected

    function MyFun(i: Integer): Integer; override;  //覆盖

    procedure MyProc; override;  //覆盖

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



{ TParent }



function TParent.MyFun(i: Integer): Integer;

begin

  Inc(i);

  Result := i;

end;



procedure TParent.MyProc;

begin

  ShowMessage('Parent');

end;



{ TChild }



function TChild.MyFun(i: Integer): Integer;

begin

  i := inherited MyFun(i);  //先调用夫类方法，被 +1；当然可以不调用

  Inc(i);                   //子类再 +1

  Result := i;

end;



procedure TChild.MyProc;

begin

  inherited;  //先调用夫类方法；当然可以不调用

  ShowMessage('Child');

end;



//测试

procedure TForm1.FormCreate(Sender: TObject);

var

  p: TParent;

  c: TChild;

begin

  p := TParent.Create;

  c := TChild.Create;



  p.MyProc;  //Parent

  c.MyProc;  //Parent; TChild



  ShowMessage(IntToStr(p.MyFun(2)));  //3

  ShowMessage(IntToStr(c.MyFun(2)));  //4



  p.Free;

  c.Free;

end;



end.