Scope-Based Memory Management

Constructors and destructors let you hook into the lifetime of an object.

By wrapping a pointer in an object, you can free memory when the object is destroyed. The compiler guarantees that this happens, even if an exception is raised.

This is often called resource acquisition is initialization (RAII) and gives you smart pointers.

C++ Example

  1. void say_hello(std::unique_ptr<Person> person) {
  2.   std::cout << "Hello " << person->name << std::endl;
  3. }
  • The std::unique_ptr object is allocated on the stack, and points to memory allocated on the heap.
  • At the end of say_hello, the std::unique_ptr destructor will run.
  • The destructor frees the Person object it points to.

Special move constructors are used when passing ownership to a function:

  1. std::unique_ptr<Person> person = find_person("Carla");
  2. say_hello(std::move(person));