Tips (1541)

Tip Rating (2):

If I want automatic garbage collection with interfaces, I use
TInterfacedObject as base class. What should I use,
if I don't want automatic destruction?
is there a similar common base class or do I
have to implement the IInterface methods myself?

I use this one:{== BaseNonRefcountIntfObjU
===========================================}
{: This unit provides a base class with a non-reference counted
implementation of IUnknown.
@author Dr. Peter Below
@desc Version 1.0 created 28 März 2002

Last modified 28 März 2002

}
{======================================================================}

unit BaseNonRefcountIntfObjU;

interface

type
  {: Derive classes that need a non-reference counted IUNknown
     implementation from this class. }
  TNonRefcountInterfacedObject = class(TObject, IUnknown)
  protected
    { IUnknown }
    function QueryInterface(const IID : TGUID; out Obj): HResult;
      stdcall;
    function _AddRef: Integer; stdcall;
    function _Release: Integer; stdcall;
  end;

implementation

uses Windows;

function TNonRefcountInterfacedObject.QueryInterface(const IID : TGUID;
  out Obj): HResult;
begin
  if GetInterface(IID, Obj) then
    Result := S_OK
  else
    Result := E_NOINTERFACE
end;

function TNonRefcountInterfacedObject._AddRef: integer;
begin
  Result := -1   // -1 indicates no reference counting is taking
    place
end;

function TNonRefcountInterfacedObject._Release: integer;
begin
  Result := -1   // -1 indicates no reference counting is taking
    place
end;

end { BaseNonRefcountIntfObjU }.