delphi - 如何在每两个不同的类上一起触发事件

Question

我在一个单元上有两个对象类，是否可以触发这两个事件？假设 FIRSTCLASS 事件被触发， SECONDCLASS 也将被触发？

假设......

//{Class 1}-------------------------------------------------------------
type
   TOnEventTrigger = procedure(Sender : Tobject; Value :integer); 
   TMyFirstClass = Class(Tcomponent)
   private
      ....
   public
      ....
      propert OnEventTrigger : TOnEventTrigger read Fevent write Fevent;
   end;

procedure TMyFirstClass.FEvnt(Sender : Tobject; Value :integer); 
begin
    // here is normaly triggers the event //
    if Assigned(OnEventTrigger) then
       OnEventTrigger(Self,FSomevalue);

    // POSTMessage(GetForegroundWindow,WM_USER+3,0,0);
    // this is what i did here to get the result of FSomevalue
    // but this is not ideal. It work only on focus window.

end;

//{Class 2}-------------------------------------------------------------

type
   TOnEventTrigger = procedure(Sender : Tobject; Value :integer); 
   TMySecondClass = Class(Tobject)
   private
      ....
   public
      ....
      property OnEventTrigger : TOnEventTrigger; read Fevent write Fevent;
   end;

procedure TMySecondClass.FEvnt(Sender : Tobject; Value :integer); 
begin
    // I wanted here to trigger, whenenver the above is fired //
    if Assigned(OnEventTrigger) then
       OnEventTrigger(Self,FSomevalue);
end;

Answer 1

您可以在创建两个类时将相同的事件处理程序分配给它们（伪代码）：

Form1 = class()
private
  { ... }
protected
  A : TMyFirstClass;
  B : TMySecondClass;
  procedure MyHandler(Sender: TObject; Value: Integer);
end;

procedure Form1.CreateForm();
Begin
     { Create A & B }
     A := TMyFirstClass.Create(Self);
     B := TMySecondClass.Create(Self);

     { Assign Event Handler to both classes }
     A.OnEventTrigger := MyHandler;
     B.OnEventTrigger := MyHandler;
End;

procedure Form1.MyHandler(Sender: TObject; Value: Integer);
Begin
     ShowMessage('Event from '+Sender.ClassName+'. Value='+IntToStr(Value));
End;

这样，当事件从任一类触发时，它将最终出现在 MyHandler() 代码中。