Generic printing with std::ostream iterators

It is pretty easy to print anything with output streams, as the STL is already shipped with many useful operator<< overloads for the most basic types. This way, data structures containing items of such types can easily be printed using the std::ostream_iterator class, which we've already done quite often in this book.

In this recipe, we will concentrate on how to do this with a custom type, and what else we can do to manipulate printing via template type choices without much code at the caller side.

How to do it...

We will play with std::ostream_iterator by enabling for combination with a new custom class and have a look into its implicit conversion capabilities, which can help us with printing:

1. The include files come first and then we declare that we use the std namespace by default:

      #include <iostream>
      #include <vector>
      #include <iterator>
      #include <unordered_map>
      #include <algorithm...