TOnUserInfoShow = procedure(userName:string;userAge:Integer)of object;//定义事件模型中的回调函数原型

  TUserInfo = class
    private
      FName:string;
      FAge:Integer;
      FOnUserInfoShow: TOnUserInfoShow;

      procedure FSetAge(theAge:Integer);
    public
      property Name:string read FName;//只读属性（私有变量）
      property Age:Integer read FAge write FSetAge;//读写属性（私有变量，私有方法）

      property OnUserInfoShow:TOnUserInfoShow  read FOnUserInfoShow write FOnUserInfoShow;//事件模型回调函数

      constructor Create;
  end;

constructor TUserInfo.Create;
begin
   Self.FName:='Terry';
   Self.FAge:=20;
end;

begin
  Self.Memo1.Lines.Add('读取只读属性姓名：'+Self.theUserInfo.Name);
end;

constructor TUserInfo.Create;
begin
   Self.FName:='Terry';
   Self.FAge:=20;
end;

begin
   Self.Memo1.Lines.Add('修改前的读写属性年龄为：'+inttostr(Self.theUserInfo.Age));
   Self.theUserInfo.Age:=30;
   Self.Memo1.Lines.Add('修改后的读写属性年龄为：'+inttostr(Self.theUserInfo.Age));
end;

procedure TFrmMain.UserInfoShow(name: string; age: Integer);
begin
   Self.Memo1.Lines.Add('用户姓名为：'+Self.theUserInfo.Name);
   Self.Memo1.Lines.Add('用户年龄为：'+inttostr(Self.theUserInfo.Age));
end;

procedure TFrmMain.FormCreate(Sender: TObject);
begin
   Self.Memo1.Color:=clBlack;
   Self.Memo1.Font.Color:=clGreen;
   theUserInfo:=TUserInfo.Create;
   Self.theUserInfo.OnUserInfoShow:=Self.UserInfoShow;
end;

begin
   Self.theUserInfo.OnUserInfoShow(Self.theUserInfo.Name,Self.theUserInfo.Age);
end;