C++17 STL Cookbook

How it works...

Usually, unique_ptr and shared_ptr just call delete on their internal pointers, whenever they ought to destroy the object they maintain. In this section, we constructed a class which can neither be allocated the C++ way using x = new Foo{123} nor can it be destructed with delete x directly.

The Foo::create_foo function just returns a plain raw pointer to a newly constructed Foo instance, so this causes no further problems because smart pointers work with raw pointers anyway.

The problem we had to deal with is that we need to teach unique_ptr and shared_ptr how to destruct an object if the default way is not the right one.

In that regard, both the smart pointer types differ a little bit. In order to define a custom deleter ...