Attach and detach many event handlers to an event at runtime

My last event chain mechanism doesn't include UnSaveEvent method. We use UnSafeEvent method for removing an event from event chain. EventId parameter is removed from event chain mechanism, so only event wrapper mechanism can be used.
There aren't any changes on SaveEvent usage, here's the example:

procedure TfrmEventChain.btnAttachEvent1Click(Sender: TObject);
begin
  SaveEvent(btnTrigger.OnClick,Event1Click,btnTrigger);
  btnTrigger.OnClick:=Event1Click;
end;

There aren't any changes on ChainedEvent usage also, here's the example:

procedure TfrmEventChain.Event1Click(Sender: TObject);
begin
  ChainedEvent(Event1Click,TComponent(Sender));
  chbEvent1.Checked:=not chbEvent1.Checked;
end;

I only add new usage of UnSaveEvent, here's the example:

procedure TfrmEventChain.btnDetachEvent1Click(Sender: TObject);
var
  NextEvent:TNotifyEvent;
begin
  NextEvent:=UnSaveEvent(Event1Click,btnTrigger);
  if SameEvent(btnTrigger.OnClick,Event1Click) then
    btnTrigger.OnClick:=NextEvent;
end;

OK, here's the unit source code for TNotifyEvent (this unit and the demo project will be sent to delphi3000 admin immediately):

unit EventChain;

interface

uses Classes, SysUtils;

type
  ECircularEventChain = class(Exception);

//EventId is removed,
//use event handler wrapper to differentiate events of single component
//that share one event handler
procedure SaveEvent(OldEvent,NewEvent:TNotifyEvent;Sender:TComponent);overload;
procedure ChainedEvent(NewEvent:TNotifyEvent;Sender:TComponent);overload
function UnSaveEvent(Event:TNotifyEvent;Sender:TComponent):TNotifyEvent;overload
function SameEvent(LeftEvent,RightEvent:TNotifyEvent):boolean;overload;

var
  EventList:TStringList;
//move declaration to implementation section after testing

implementation

type
  TEventListCleaner = class(TComponent)
  protected
    procedure Notification(AComponent: TComponent;Operation: TOperation);override;
  end;

var
  EventListCleaner:TEventListCleaner;

procedure SaveEvent(OldEvent,NewEvent:TNotifyEvent;Sender:TComponent);
var
  EventName:string;
  EventString:string;
  i,u:integer;
  SenderString:string;
begin
  if Assigned(OldEvent) and Assigned(NewEvent) and Assigned(Sender) and (@OldEvent<>@NewEvent) then
  begin
    EventString:=IntToStr(Integer(TMethod(NewEvent).Data))+'.'+
    IntToStr(Integer(TMethod(NewEvent).Code));
    u:=EventList.Count-1;
    SenderString:=IntToStr(Integer(Sender));
    //check for circular event chain
    for i:=0 to u do
    begin
      EventName:=EventList.Names[i];
      if (pos(SenderString,EventName)=1)and
      (EventList.Values[EventName]=EventString) then
        raise ECircularEventChain.Create('Circular event chain found!');
    end;
    EventName:=SenderString+'.'+IntToStr(Integer(@NewEvent));
    EventString:=IntToStr(Integer(TMethod(OldEvent).Data))+'.'+
    IntToStr(Integer(TMethod(OldEvent).Code));
    EventList.Values[EventName]:=EventString;
    Sender.FreeNotification(EventListCleaner);
  end;
end;

procedure ChainedEvent(NewEvent:TNotifyEvent;Sender:TComponent);
var
  EventName:string;
  OldEvent:TNotifyEvent;
  EventString:string;
  Separator:integer;
begin
  if Assigned(NewEvent) and Assigned(Sender) then
  begin
    EventName:=IntToStr(Integer(Sender))+'.'+IntToStr(Integer(@NewEvent));
    EventString:=EventList.Values[EventName];
    if (EventString<>'') then
    begin
      Separator:=pos('.',EventString);
      TMethod(OldEvent).Data:=Pointer(StrToInt(Copy(EventString,1,Separator-1)));
      TMethod(OldEvent).Code:=Pointer(StrToInt(Copy(EventString,Separator+1,length(EventString)-Separator)));;
      if Assigned(OldEvent) then
        OldEvent(Sender);
    end;
  end;
end;

function UnSaveEvent(Event:TNotifyEvent;Sender:TComponent):TNotifyEvent;overload
var
  i,u,pstn,separator:integer;
  EventName,EventString,EventCodeString,SenderString,NextEventString:string;
begin
  Result:=nil;
  if Assigned(Event) and Assigned(Sender) then
  begin
    NextEventString:=IntToStr(Integer(TMethod(Result).Data))+'.'+
    IntToStr(Integer(TMethod(Result).Code));
    EventCodeString:=IntToStr(Integer(TMethod(Event).Code));
    EventString:=IntToStr(Integer(TMethod(Event).Data))+'.'+
    EventCodeString;
    SenderString:=IntToStr(Integer(Sender));
    u:=EventList.Count-1;
    pstn:=EventList.IndexOfName(SenderString+'.'+EventCodeString);
    for i:=u downto 0 do
    begin
      EventName:=EventList.Names[i];
      if (pos(SenderString,EventName)=1)and(EventList.Values[EventName]=EventString)then
      begin
        //Next event found redirect next event
        if pstn>=0 then
          NextEventString:=EventList.Values[SenderString+'.'+EventCodeString];
        EventList.Values[EventName]:=NextEventString;
      end;
    end;
    if pstn>=0 then
    begin
      NextEventString:=EventList.Values[SenderString+'.'+EventCodeString];
      Separator:=pos('.',NextEventString);
      TMethod(Result).Data:=Pointer(StrToInt(Copy(NextEventString,1,Separator-1)));
      TMethod(Result).Code:=Pointer(StrToInt(Copy(NextEventString,Separator+1,length(NextEventString)-Separator)));;
      EventList.Delete(pstn);
    end;
  end;
end;

function SameEvent(LeftEvent,RightEvent:TNotifyEvent):boolean;
begin
  with TMethod(LeftEvent) do
    Result:=(Data=TMethod(RightEvent).Data)and(Code=TMethod(RightEvent).Code);
end;

end.