Understanding RAII ​

Resource Acquisition is Instantiation (RAII)

When you acquire some resource (memory on the heap e.g. dynamically allocated), or a mutex lock, or a thread. When resources are acquired, if they're not cleaned up when they go out of scope then you'll get memory leaks.

RAII is used to make code that acuqires a resource safer and easier to write.

RAII is when you acquire resouces in a constructor and release (or delete) the resource in the corresponding destructor.

What is a Resource ​

• something that must be acquired before use
• In limited supply
• Examples: heap memory, files, sockets, mutexes

A program has to acquire memory from the OS (for heap allocation), and the program must eventually give them back to the OS.

Benefits of RAII

• Dont have to worry about the resource lifetime
• Instead, think about object lifetime.

When using RAII patterns, never use:

• new
• free
• delete
• explicitly lock/unlock a mutex

Examples of RAII classes:

• std::vector
• std::string
• std::unique_ptr
• std::shared_ptr
• std::lock_guard, std::scoped_lock, and std::unique_lock

ADDITIONAL RESOURCES

• https://www.youtube.com/watch?v=q6dVKMgeEkk