Mastering Rust - Second Edition

Lifetimes

The third piece in Rust's compile time memory safety puzzle is the idea of lifetimes and the related syntactic annotation for specifying lifetimes in code. In this section, we'll explain lifetimes by stripping them down to the basics.

When we declare a variable by initializing it with a value, the variable has a certain lifetime, beyond which it is invalid to use it. In general programming parlance, the lifetime of a variable is the region in code in which the variable points to a valid memory. If you have ever programmed in C, you should be acutely aware of the case with lifetimes of variables: every time you allocate a variable with malloc, it should have an owner, and that owner should reliably decide when that variable's life ...