Modern C++ Programming Cookbook

How to do it...

Take the following steps to implement the pimpl idiom, exemplified here by refactoring the control class shown earlier:

1. Put all private members, both data and functions, into a separate class. We will call this the pimpl class and the original class the public class.
2. In the header file of the public class, put a forward declaration to the pimpl class:

        // in control.h        class control_pimpl;

3. In the public class definition, declare a pointer to the pimpl class using a unique_ptr. This should be the only private data member of the class:

        class control        {          std::unique_ptr<            control_pimpl, void(*)(control_pimpl*)> pimpl;        public:          control();          void set_text(std::string_view text);          void resize(int const w, int const h); void show(); ...