Mastering Rust - Second Edition

Specifying lifetime bounds on generic types

Apart from using traits to constrain the types that can be accepted by a generic function, we can also constrain generic type parameters using lifetime annotations. For instance, consider we have a logger library where the Logger object is defined as follows:

// lifetime_bounds.rsenum Level {    Error}struct Logger<'a>(&'a str, Level);fn configure_logger<T>(_t: T) where T: Send + 'static {    // configure the logger here}fn main() {    let name = "Global";    let log1 = Logger(name, Level::Error);    configure_logger(log1);}

In the preceding code, we have a Logger struct with its name and a Level enum. We also have a generic function called configure_logger that takes a type T that is constrained with Send + 'static ...