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I am trying to overload an assignment operator in a cpp file for a nested template class.

My header file looks something like this:

template <class T>
class Outer:
private:
   // some member variables
public:
   /*
   * Other functions here
   */

   template <class T>
   class Inner:
      Inner & Inner :: operator = (const Inner & rhs);

I can't, however, figure out what my cpp file should look like. This is what I have:

template <class T>
Outer<T>::Inner<T>:: Inner<T> & Inner<T> :: operator = (const Inner<T> & rhs)
{
   // code is here
}

This gives me the error:

Iterator is not a template (C/C++ 864)

on the parts of my code surrounded by *

Outer<T>::Inner<T>::Inner<T> & **Inner<T>** :: operator = (const **Inner<T>** & rhs)

I would rather not make the operator overloads inline if I can avoid it. Help!

bdcrisco98
  • 11
  • 1
    Trying to write definition of functions for template class declared in a header in cpp file looks strange. [c++ - Why can templates only be implemented in the header file? - Stack Overflow](https://stackoverflow.com/questions/495021/why-can-templates-only-be-implemented-in-the-header-file) – MikeCAT Apr 01 '22 at 12:58
  • `T` from `Inner` shadows `T` from `Outer`... – Jarod42 Apr 01 '22 at 15:30

2 Answers2

2

Class template must be defined in header file. I am not sure to understand the question but the below code compile:

template <class T>
class Outer {
 public:
  template <class V>
  class Inner {
    Inner& operator=(const Inner& rhs);
};
};

template <class T>
template <class V>
Outer<T>::Inner<V>& Outer<T>::Inner<V>::operator=(const Outer<T>::Inner<V>& rhs) {
  //do something
   return *this;
}

int main() {
        Outer<int> o;
}
GTA
  • 253
  • 4
  • 13
0

Working Header File:

template <class T>
class Outer
{
private:
   // some member variables
public:
   /*
   * Other functions here
   */

   class Inner
   {
   private:
      T t;
   public:
      Inner & operator = (const Inner & rhs);
   };
};

Working cpp file:

template <class T>
Outer<T>::Inner & Outer<T>::Inner::operator = (const Inner & rhs)
{
   // code is here
}
bdcrisco98
  • 11