C++ Coding Standards: 101 Rules, Guidelines, and Best Practices

56. Whenever it makes sense, provide a no-fail swap (and provide it correctly)

Summary

swap is both a lightweight and a workhorse: Consider providing a swap function to efficiently and infallibly swap the internals of this object with another’s. Such a function can be handy for implementing a number of idioms, from smoothly moving objects around to implementing assignment easily to providing a guaranteed commit function that enables strongly error-safe calling code. (See also Item 51.)

Discussion

A swap function typically looks like this, where U is some user-defined type:

For primitive types and for standard containers, std::swap will do. ...