Observer pattern using anonymous methods

Observer.pas

type
  IObservable<T> = interface(IInterface)
    ['{C783F241-8BC8-401E-9666-D4DCE08A711B}']
    procedure NotifyAll(const AValue: T);
    procedure Register(const AObserver: TProc<T>);
    procedure Unregister(const AObserver: TProc<T>);
    procedure UnregisterAll;
  end;

  TObservable<T> = class sealed(TInterfacedObject, IObservable<T>)
  strict private
    FObservers: TArray<TProc<T>>;
  public
    procedure NotifyAll(const AValue: T);
    procedure Register(const AObserver: TProc<T>);
    procedure Unregister(const AObserver: TProc<T>);
    procedure UnregisterAll;
  end;

implementation

{ TObservable }

procedure TObservable<T>.NotifyAll(const AValue: T);
var
  Observer: TProc<T>;
begin
  for Observer in FObservers do
    Observer(AValue);
end;

procedure TObservable<T>.Register(const AObserver: TProc<T>);
begin
  TArray.Add<TProc<T>>(FObservers, AObserver);
  TArray.Sort<TProc<T>>(FObservers);
end;

procedure TObservable<T>.Unregister(const AObserver: TProc<T>);
begin
  TArray.Remove<TProc<T>>(FObservers, AObserver);
end;

procedure TObservable<T>.UnregisterAll;
var
  Observer: TProc<T>;
begin
  for Observer in FObservers do
    Unregister(Observer);
end;

end.