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/*=========================================================================
Program: Visualization Toolkit
Module: vtkNew.h
Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
All rights reserved.
See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
This software is distributed WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE. See the above copyright notice for more information.
=========================================================================*/
// .NAME vtkNew - Allocate and hold a VTK object.
// .SECTION Description
// vtkNew is a class template that on construction allocates and
// initializes an instance of its template argument using T::New().
// It assumes ownership of one reference during its lifetime, and calls
// T->Delete() on destruction.
//
// Automatic casting is intentionally unavailable, calling GetPointer() will
// return a raw pointer. Users of this method should ensure that they do not
// return this pointer if the vtkNew will go out of scope without
// incrementing its reference count using vtkSmartPointer or similar.
//
// \code
// vtkNew<vtkClass> a;
// a->SomeMethod();
//
// vtkSmartPointer<vtkClass> b = a.GetPointer();
// b->SomeOtherMethod();
// \endcode
//
// It should be noted that vtkNew is not a drop in replacement for
// vtkSmartPointer as it is not implicitly cast to a pointer in functions
// requiring a pointer. The GetPointer() method must be used, for example,
//
// \code
// vtkNew<vtkRenderer> ren;
// vtkNew<vtkRenderWindow> renWin;
// renWin->AddRenderer(ren.GetPointer());
// vtkNew<vtkRenderWindowInteractor> iren;
// iren->SetRenderWindow(renWin.GetPointer());
// \endcode
//
// .SECTION See Also
// vtkSmartPointer vtkWeakPointer
#ifndef vtkNew_h
#define vtkNew_h
#include "vtkIOStream.h"
class vtkObjectBase;
template <class T>
class vtkNew
{
// Description:
// Compile time checking that the class is derived from vtkObjectBase.
void CheckObjectBase(vtkObjectBase*) {}
public:
// Description:
// Create a new T on construction.
vtkNew() : Object(T::New())
{
this->CheckObjectBase(this->Object);
}
// Description:
// Deletes reference to instance of T on destruction.
~vtkNew()
{
T* obj = this->Object;
if (obj)
{
this->Object = 0;
obj->Delete();
}
}
// Description:
// Enable pointer-like dereference syntax. Returns a pointer to the contained
// object.
T* operator->() const
{
return this->Object;
}
// Description:
// Get a raw pointer to the contained object. When using this function be
// careful that the reference count does not drop to 0 when using the pointer
// returned. This will happen when the vtkNew object goes out of
// scope for example.
T* GetPointer() const
{
return this->Object;
}
T* Get() const
{
return this->Object;
}
private:
vtkNew(vtkNew<T> const&); // Not implemented.
void operator=(vtkNew<T> const&); // Not implemented.
T* Object;
};
// Description:
// Streaming operator to print vtkNew like regular pointers.
template <class T>
inline ostream& operator << (ostream& os, const vtkNew<T>& p)
{
return os << p.GetPointer();
}
#endif
// VTK-HeaderTest-Exclude: vtkNew.h
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