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unit Unit1;

interface

type TTestEvent = procedure(Sender: TObject) of object;

type TKlasse = class
  private
    FTestEvent: TTestEvent;
  published
    property OnTestEvent: TTestEvent read FTestEvent write FTestEvent;
end;

type THandler = class
  public
    procedure HandleEvent(Sender: TObject);
end;

implementation

{ THandler }

procedure THandler.HandleEvent(Sender: TObject);
begin
  // nix
end;

var
  Klasse: TKlasse;
  Handler: THandler;
begin
  Klasse := TKlasse.Create;
  try
    Handler := THandler.Create;
    try
      Klasse.OnTestEvent := Handler.HandleEvent;
      Klasse.OnTestEvent := nil;
    finally
      Handler.Free;
    end;
  finally
    Klasse.Free;
  end;
end.					

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unit Unit2;

interface

uses Classes, Contnrs;

type TTestEvent = procedure(Sender: TObject) of object;

type TKlasse = class
  private
    FTestEventHandler: TObjectList;
  public
    constructor Create;
  published
    procedure AddTestHandler(Handler: TTestEvent);
    procedure RemoveTestHandler(Handler: TTestEvent);
end;

type THandler = class
  public
    procedure HandleEvent(Sender: TObject);
end;

implementation

{ THandler }

procedure THandler.HandleEvent(Sender: TObject);
begin
  // nix
end;

{ TKlasse }

procedure TKlasse.AddTestHandler(Handler: TTestEvent);
begin
  FTestEventHandler.Add(Handler);
end;

constructor TKlasse.Create;
begin
  inherited Create;

  FTestEventHandler := TObjectList.Create;
end;

procedure TKlasse.RemoveTestHandler(Handler: TTestEvent);
begin
  FTestEventHandler.Remove(Handler);
end;

var
  Klasse: TKlasse;
  Handler: THandler;
begin
  Klasse := TKlasse.Create;
  try
    Handler := THandler.Create;
    try
      Klasse.AddTestHandler(Handler.HandleEvent);
      Klasse.RemoveTestHandler(Handler.HandleEvent);
    finally
      Handler.Free;
    end;
  finally
    Klasse.Free;
  end;
end.					

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procedure TMyObject.fireXYevent(const Params);
var
    X:Integer;
begin
    For X := 0 to High(listenerXYevent) do
        listenerXYevent[X](params);
end;					

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type
    TXYevent = procedure (const params): of object;
    TXYeventArray = array of TXYevent;

type
    TMyObject = class(TFoo)
    private
        {...}
        listenerXYevent: TXYeventArray;
        {...}
        procedure fireXYevent(const params);
        {...}
    public
        {...}
        procedure addXYlistener(listener: TXYevent);
        procedure removeXYlistener(listener: TXYevent);
        {...}
    end;					

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constructor TMyObject.Create;
begin
    SetLength(fSomeField, 1);
end;

destructor TMyObject.Destroy;
Begin
    while Length(FSomeField) > 0 do
    Begin
        FSomeField[Length(FSomeField)].Free; //Index out of Bounds-Exception
    end;
end;					

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type TEvent = procedure of object;
type TEvents = array of TEvent;

type
  TKlasse = class
  private
    FEvents: TEvents;
    FEventCount: Integer;
  public
    procedure AddEventListener(Listener: TEvent);
    procedure RemoveEventListener(Listener: TEvent);
    procedure RemoveAllEventListener;
end;

[...]

procedure TKlasse.RemoveEventListener(Listener: TEvent);
var
  I: Integer;
begin
  for I := Low(FEvents) to High(FEvents) do
  begin
    if (Assigned(FEvents[I])) and 
       (FEvents[I] = Listener) then
    begin
      FEvents[I] := nil;
      Dec(FEventCount);
      Break;
    end;
  end;
end;