Delphi XE2中的类助手和类拦截器

Question

我有一段代码如下所示:

接口部分:

TControlOrganizer = class(TComponent)  // a kind of List of TControl
private
  FList : TList;  //Handling list of TControl
  ..............
end;

TControlHelperAdd = class // Just for separating value entered by user and value produced by code
  private
    FOrganizer : TControlOrganizer;
    FOrigValue : String;
    FUserValue : String;
end;

TControlHelper = class helper for TControl  //Basic helper for TControl
  private
    class var
      FAddProp : TControlHelperAdd;
  protected
    procedure SetOrganizer(Value : TControlOrganizer);
    function getOrganizer:TControlOrganizer;
  public
    class Constructor doinit;
    class Destructor deinit;
    procedure OrganizerChanged;virtual;
  published
    Property Organizer:TControlOrganizer read getOrganizer write setOrganizer; //Problem No.1
  end;

//Helper for CustomEdit inherited from TControlHelper
TCustomEditHelper = class helper(TControlHelper) for TCustomEdit
  protected
    procedure OrganizerChanged;override;
  end;
//TEdit : interceptor
TEdit= class(StdCtrls.TEdit)
  protected
    procedure Change;override;  //problem No.3
end;

实施部分:

{TControlHelper}

class Constructor TControlHelper.doinit;
begin
  FAddProp :=TControlHelperAdd.Create;
end;

class Destructor TControlHelper.deinit;
begin
  FreeAndNil(FAddProp);
end;

procedure TControlHelper.OrganizerChanged;
begin
end;

procedure TControlHelper.SetOrganizer(Value : TControlOrganizer);
begin
  if FAddProp.FOrganizer<>value then begin
     if assigned(FAddProp.FOrganizer) then begin
       FAddProp.FOrganizer.remove(self);
     end;
     FAddProp.FOrganizer:=value;
     if assigned(FAddProp.FOrganizer) then begin
       FAddProp.FOrganizer.Add(self);
     end;
     OrganizerChanged;  //Problem No.2
  end;
end;

function TControlHelper.getOrganizer:TControlOrganizer;
begin
  result:=FAddProp.FOrganizer;
end;

{TCustomEditHelper}
procedure TCustomEditHelper.OrganizerChanged; //problem No.2
begin
  if assigned(FAddProp) then begin
    if assigned(Organizer) then begin
      FAddProp.FOrigValue:=Text;
      FAddProp.FUserValue:=Text;
    end;
  end;
end;

{TEdit = Interceptor} 
procedure TEdit.Change; //Problem No.3
begin
  inherited Change;
  FAddProp.FUserValue:=Text;
end;

我发现了3个我无法解决的问题.

问题1:已发布的属性属性未显示在Object Inspector中.我想我犯了一个错误并忘了这里的东西.

问题2:如上所示,来自类助手的重写方法没有触发(不起作用).

问题3:如上所示,来自拦截器类的重写方法没有触发(不起作用).

有人可以帮我找出问题吗？感谢您的帮助,抱歉我的英语不好.

Answer 1

问题1

辅助对象中的已发布属性未显示在对象检查器中.

那就对了.在助手中声明的属性永远不会出现在对象检查器中.

问题2

虚拟方法对类助手没有影响.

再次,这是设计的.虽然编译器允许您在助手中定义虚方法,但它没有任何效果.为了TCustomEditHelper.OrganizerChanged触发,TCustomEditHelper需要成为目标对象的主动帮助者.

问题3

Change拦截TEdit类的方法不会触发.

那是因为你没有实例化截获的TEdit.如果实例化正确的类,即您定义的拦截器类,则该方法将触发.