Question

I have following template code:

class ClassName{};

template <class T>
class TemplatePtr
{
public:
    void operator=(T* p)
    {

    }
};

class TemplatePtr_ClassName: public TemplateePtr<ClassName>
{
public:
    ~TempaltePtr_ClassName();
};


void Test()
{
    TemplatePtr_ClassName data;
    data = new ClassName;
}

but compile fails with error message (VS2008):

error C2679: binary ‘=’ : no operator found which takes a right-hand operand of type >>’ClassName *’ (or there is no acceptable conversion)

Why it won’t work as I have defined an operator in the template base class?

Answer 1

operator = is always hidden by the derived class implementation unless explicit using declaration is provided. This is true for both class templates and ordinary classes.

BTW, your declaration of operator= is very nonstandard. It is usually declared so for a class ‘A’.

A& operator=(A const &);

Here is something that may be what you are looking for (and compiles)

template <class T> 
class TemplatePtr 
{ 
public: 
    TemplatePtr& operator=(TemplatePtr const &) 
    {return *this;} 
}; 

template<class T>
class TemplatePtr_ClassName: public TemplatePtr<T> 
{ 
public:
   ~TemplatePtr_ClassName(){};
   TemplatePtr_ClassName& operator=(TemplatePtr_ClassName const &that){
      TemplatePtr<T>::operator=(that);        // invoke base class assignment operator
      return *this;
   }
}; 


int main() 
{ 
    TemplatePtr_ClassName<int> data; 
    data = *new TemplatePtr_ClassName<int>; 
    // delete stuff
}