spring4d-不可能使用弱＆lt;共享＆lt; tobject＆gt;

Question

我想创建一个连接提供商，它会发出共享的＆lt; t＆gt;并坚持一个弱者＆lt; t＆gt;但是，即使仅创建了1个实例，但仍有2种销毁的尝试。

我在下面包括一个基本示例。

  TMyObj = class
  private
    class var
      fNextId: Integer;
    var
      fId: Integer;
  public
    constructor Create;
    destructor Destroy; override;
  end;

  IProv = interface
  ['{0497DFE9-A77C-4250-82AF-FDA3823A91EC}']
    function Get: Shared<TMyObj>;
    function GetNew: Shared<TMyObj>;
  end;

  TProv = class(TInterfacedObject, IProv)
  private
    fInstance: Weak<TMyObj>;
  protected
    function Get: Shared<TMyObj>;
    function GetNew: Shared<TMyObj>;
  end;

  THolder = class
  private
    fO: Shared<TMyObj>;
  public
    constructor Create(O: Shared<TMyObj>);
  end;

var
  Form2: TForm2;

implementation

{$R *.dfm}

procedure TForm2.Button1Click(Sender: TObject);
begin
  var P:=TProv.Create as IProv;

  var H:=THolder.Create(P.Get);
  var H2:=THolder.Create(P.Get);
  FreeAndNil(H);
  FreeAndNil(H2);
  OutputDebugString('End');
end;

{ TMyObj }

constructor TMyObj.Create;
begin
  fId:=InterlockedIncrement(fNextId);
  OutputDebugString(PChar(fId.ToString+' Creating On '+GetCurrentThreadId.ToString));
end;

destructor TMyObj.Destroy;
begin
  OutputDebugString(PChar(fId.ToString+' Destroying On '+GetCurrentThreadId.ToString));
  inherited;
end;

{ TProv }

function TProv.Get: Shared<TMyObj>;
begin
  if fInstance.IsAlive then
    Exit(fInstance.Target);

  Result:=GetNew;
  fInstance:=Result;
end;

function TProv.GetNew: Shared<TMyObj>;
begin
  Result:=TMyObj.Create;
end;

{ THolder }

constructor THolder.Create(O: Shared<TMyObj>);
begin
  fO:=O;
end;

然后，我认为那个弱＆lt; t＆gt;仅适用于界面，因此更改了实现，以保持弱点; iShared＆lt; t＆gt;＆gt;但是，当我称弱的词时，false返回。