IMyIntf = interface(IUnknown)
...
end;

var
  Intf: IMyIntf;
begin
  Intf := ...
...
end; // Здесь компилятор вставляет код финализации Intf

IMyIntf = interface(IInterface)
...
end;

var
  Intf: IMyIntf;
begin
  Intf := ...
...
end; // А здесь - нет.

 Ins

ITreeNode = interface
  ...
  property Nodes[Index: Integer]: ITreeNode read GetNode;
  property NodeByName[AName: String]: ITreeNode read GetNodeByName;
  ...
end;

Root.NodeByName['SomeNode'].AddNode(...);

Root.GetNodeByName('SomeNode', Node);
Node.AddNode(...);
Node := nil;

 Ins

TMyInterfacedObject = class(TObject, IInterface)
protected
  FRefCount: Integer;
  FDestroyed: Boolean;
  function QueryInterface(const IID: TGUID; out Obj): HResult; stdcall;
  function _AddRef: Integer; stdcall;
  function _Release: Integer; stdcall;
public
  procedure BeforeDestruction; override;
  procedure FreeInstance; override;
  property RefCount: Integer read FRefCount;
end;

procedure TMyInterfacedObject.BeforeDestruction;
begin
  FDestroyed := True;
end;

procedure TMyInterfacedObject.FreeInstance;
begin
  if RefCount = 0 then
    inherited FreeInstance;
end;

function TMyInterfacedObject.QueryInterface(const IID: TGUID; out Obj): HResult;
begin
  Result := IfThen(GetInterface(IID, Obj), 0, E_NOINTERFACE);
end;

function TMyInterfacedObject._AddRef: Integer;
begin
  Result := InterlockedIncrement(FRefCount);
end;

function TMyInterfacedObject._Release: Integer;
begin
  Result := InterlockedDecrement(FRefCount);
  if (Result = 0) and FDestroyed then
    FreeInstance;
end;

 Ins

  FuncThatReturnsInterface(...);

  Temp := FuncThatReturnsInterface(...);
  Finalize(Temp);

  try
    Temp := FuncThatReturnsInterface(...);
  finally
    Finalize(Temp);
  end;

Temp := FuncThatReturnsInterface(...);
  try
  finally
    Finalize(Temp);
  end;

  FinalizeInterface(FuncThatReturnsInterface(...));

  // здесь установка параметров функции
  call FuncThatReturnsInterface
  call FinalizeInterface   // функция вернёт интерфейс в EAX, его же и передадим в функцию очистки (может сюда подойдёт и обычный Finalize)
  ... // продолжение работы

 Александр Алексеев

CreateObjects;
Intf := GetInterface;
...
Intf := nil;
{ и потом можно }
DestroyObjects;

  objTest := TTest.Create(nil);
  intfTest := objTest;
  objTest.Free;

function TComponent._Release: Integer;
begin

  if FVCLComObject = nil then
    Result := -1   // -1 indicates no reference counting is taking place
  else
    Result := IVCLComObject(FVCLComObject)._Release;
end;

objTest := TTest.Create(nil);
intfTest := objTest;

   intfTest := TTest.Create(nil);
  self.GetInterface.Hello;  
  IInterfaceComponentReference(intfTest).GetComponent.Free;

   intfTest := TTest.Create(nil);
  self.GetInterface.Hello;  
  intfTest.GetSelf.Free;

type

  ITest = interface(IInterface)
    ['{57ACE49A-3DC2-46E6-815B-834444AAD793}']
    function GetSelf: TObject;
    procedure Hello;
  end;

  TTest = class(TComponent, ITest)
    function GetSelf: TObject;
    procedure Hello;
  end;

  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    objTest: TTest;
    intfTest: ITest;
    function GetInterface: ITest;
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

{ TTest }

function TTest.GetSelf: TObject;
begin
  Result:=Self;
end;

procedure TTest.Hello;
begin
  ShowMessage('Hello');
end;

function TForm1.GetInterface: ITest;
begin
  Result := self.intfTest;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  intfTest := TTest.Create(nil);
  self.GetInterface.Hello;
  intfTest.GetSelf.Free; //подсчёт ссылок не работает => удаляем объект сами

  with TButton.Create(Application) do begin
    Parent := self;
  end;

end;

end.

type

  ITest = interface(IInterface)
    ['{57ACE49A-3DC2-46E6-815B-834444AAD793}']
    function GetSelf: TObject;
    procedure Hello;
  end;

  TTest = class(TComponent, ITest)
  public
    constructor Create(AOwner: TComponent); override;
    function GetSelf: TObject;
    procedure Hello;
    procedure Release;
  end;

  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    objTest: TTest;
    intfTest: ITest;
    function GetInterface: ITest;
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

{ TTest }

constructor TTest.Create(AOwner: TComponent);
begin
  inherited;
  _AddRef;  // искуственно увеличиваем RefCount
end;

function TTest.GetSelf: TObject;
begin
  Result:=Self;
end;

function TForm1.GetInterface: ITest;
begin
  Result := self.intfTest;
end;

procedure TTest.Hello;
begin
  ShowMessage('Hello');
end;

procedure TTest.Release;
begin
  _Release;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  objTest := TTest.Create(self);
  intfTest := objTest;
  self.GetInterface.Hello;
  objTest.Release;  // надо "подчистить" за собой

  with TButton.Create(self) do begin
    Parent := self;
  end;

end;

end.

  objTest := TTest.Create(self);
  objTest.Hello;
  objTest.Free;

  intfTest := TTest.Create(self);  //если вместо self использовать nil, то будет утечка памяти (FastMM4 ругается)
  self.GetInterface.Hello;

type

  ITest = interface(IInterface)
    ['{57ACE49A-3DC2-46E6-815B-834444AAD793}']
    function GetSelf: TObject;
    procedure Hello;
  end;

  TTest = class(TComponent, ITest)
    function GetSelf: TObject;
    procedure Hello;
  end;

  ...
function TTest.GetSelf: TObject;
begin
  Result:=Self;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  intfTest := TTest.Create(self);
  objTest:=TTest(intfTest.GetSelf);
  objTest.Hello;
end;

private
  FViewer: IViewer;
  procedure SetViewer(const Value: IViewer);
published
  property Viewer: IViewer read FViewer write SetViewer;

 Fisher