接口基类IUnknown(Interface)整型变量引用计数FRefCount(整型变量)初始化的疑惑

unit Unit1;



interface



uses

  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

  Dialogs, StdCtrls;



type

  TForm1 = class(TForm)

  private

    { Private declarations }

  public

    { Public declarations }

  end;



  IFormattedNumber = interface

    function FormattedString : String;

  end;



  TFormattedInteger = class(TObject,IFormattedNumber)

  private

    FValue : Integer;

    FRefCount : Integer;//引用计数

  public

    constructor Create(AValue : Integer);

     //IUnknown 接口

    function QueryInterface(const IID : TGUID;out Obj): HResult; stdcall;

    function _AddRef : Integer; Stdcall;

    function _Release : Integer; stdcall;

    //IFormattedNumber 接口

    function FormattedString : String;

    procedure SetValue(AValue : Integer);

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}

constructor TFormattedInteger.Create(AValue : Integer);

begin

  inherited Create;

  FValue := AValue;

end;



function TFormattedInteger.QueryInterface(const IID: TGUID; out Obj): HResult; stdcall;

const

  E_NOINTERFACE = $80004002;

begin

  if GetInterface(IID,Obj) then

    Result := 0

  else

    Result := E_NOINTERFACE;

end;



function TFormattedInteger._AddRef: Integer;stdcall;

begin

  Inc(FRefCount);

  Result := FRefCount;

end;



function TFormattedInteger._Release: Integer; stdcall;

begin

  Dec(FRefCount);

  Result := FRefCount;

  If FRefCount = 0 then

    Destroy;

end;



//IFormattedNumber接口

function TFormattedInteger.FormattedString : String;

begin

  Result := 'The value is' + IntToStr(FValue);

end;



procedure TFormattedInteger.SetValue(AValue : Integer);

begin

  FValue := AValue;

end;



end.