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Why do I need a protected destructor?

A protected destructor is used to prohibit from the memory allocation on stack or in the static data segment and from the explicit deallocation by delete. I.e. an object can be created on the heap but delete cannot be called for its pointer.

Practical use of the protected destructor (usually it's also virtual):

• base classes with object count variable
• classes used in the environment with memory garbage collection
• any other classes where explicit object deletion is not acceptable

class TestClass
{
public:
   TestClass() {}
   void Release()
   {
      //whatever required
      delete this;
   }

protected:
   virtual ~TestClass() {}
};

int main(int argc, char** argv[])
{
//   TestClass tc; // gives error C2248: 'TestClass::~TestClass' : cannot access
                   // protected member declared in class 'TestClass'

   TestClass* pTC = new TestClass;

//   delete pTC; // gives the same error

   pTC->Release();
   return 0;
}

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