Mastering the C++17 STL

Smart pointers never forget

The idea of a "smart pointer" type (not to be confused with a "fancy pointer" type, which we'll cover in Chapter 8, Allocators) is that it's a class--typically a class template--which behaves syntactically just like a pointer, but whose special member functions (construction, destruction, and copying/moving) have additional bookkeeping to ensure certain invariants. For example, we might ensure the following:

• The pointer's destructor also frees its pointee--helping to solve memory leaks
• Maybe the pointer cannot be copied--helping to solve use-after-free
• Or maybe the pointer can be copied, but it knows how many copies exist and won't free the pointee until the last pointer to it has been destroyed
• Or maybe the pointer ...