Passing std::string as parameter

This protip is a note for me to not forget:

1. Using the string as an id (will not be modified). Passing it in by const reference is probably the best idea here: (std::string const&)

2. Modifying the string but not wanting the caller to see that change. Passing it in by value is preferable: (std::string)

3. Modifying the string but wanting the caller to see that change. Passing it in by reference is preferable: (std::string &)

4. Sending the string into the function and the caller of the function will never use the string again. Using move semantics might be an option (std::string &&)

Source: http://stackoverflow.com/a/10789797/1996540