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c++listtemplatesoperator-keyword
Tom
Tom

Reputation: 3418

C++ Overload operator << with something other than ostream

I'm trying to show off variety on a piece of course work and hoped to use the << operator to easily add variables to a list. Eg:

UpdateList<string> test;
test << "one" << "two" << "three";

My problem, is that EVERY SINGLE example of the << operator is to do with ostream.

My current attempt is: 

template <class T> class UpdateList
{
     ...ect...

     UpdateList<T>& operator <<(T &value)
     {
          return out;
     }
}

Does anyone know how I can achieve this, or is it actually not possible inside C++?

Upvotes: 0

Views: 104

Answers (3)

πάντα ῥεῖ
πάντα ῥεῖ

Reputation: 1

You' ll need an overloaded operator<<() outside the class:

template<typename T>
UpdateList<T>& operator<<(UpdateList<T>& out, const T& value)
{
    return out;
}

Upvotes: 1

Zac Howland
Zac Howland

Reputation: 15870

You would (typically) want to declare it as a non-class member:

template<typename T>
UpdateList<T>& operator<<(UpdateList<T>& lst, const T& value)
{
    lst.add(value); // whatever your add/insert method is goes here
    return lst;
}

Upvotes: 1

ForEveR
ForEveR

Reputation: 55897

You should use const T& value. Following fragment of code should work fine

UpdateList<T>& operator << (const T& value)
{
   // push to list
   return *this;
}

or

UpdateList<T>& operator << (T value)
{
   // push to list
   return *this;
}

in C++11 (thanks to rightfold)

Upvotes: 6

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