[Insight-developers] Why does ObjectFactoryBase::CreateInstance call o->Register() for objects it creates?

[Bradley Lowekamp]

Kent,

The same methodology is used in the itkNewMacro, which is used in all news:

define itkSimpleNewMacro(x)                                   \
  static Pointer New(void)                                     \
    {                                                          \
    Pointer smartPtr = ::itk::ObjectFactory< x >::Create();    \
    if ( smartPtr.GetPointer() == NULL )                       \
      {                                                        \
      smartPtr = new x;                                        \
      }                                                        \
    smartPtr->UnRegister();                                    \
    return smartPtr;                                           \
    }


I also wonder why this is needed. I myself would have just returned with the following:

 if ( newobject )
      {
      return LightObject::Pointer(newobject );
      }

But there  is likely a case where the current implementation is needed, or perhaps it's just legacy from some ancient compiler.

Brad

On Aug 9, 2011, at 2:32 PM, Williams, Norman K wrote:

> OK here's a simple question: Why does ObjectFactoryBase::CreateInstance
> call newobject->Register()?
> 
> ALL of the remaining leaks reported by valgrind in the new FEM framework
> happen because CreateInstance returns an object with a reference count of
> 2.
> 
> Corrolary question: ObjectFactoryBase is only used a few places:
> TransformIOBase, SpatialObjectDuplicator and the FEM Framework. In the
> first 2 places, LightObject::Unregister() is called to correct this
> problem.
> 
> Is there any rational reason CreateInstance should call Register() on the
> objects it returns?
> 
> 
> 
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