Rust Essentials - Second Edition

Testing for failure

However, in most cases, we would like to attempt to recover from the error and let the program continue. We have already seen the basic techniques used in Rust to do just this in the Result and Option section in Chapter 4, Structuring Data and Matching Patterns, and in the section Generic data structures and functions in this chapter.

Both the Option and Result types are generic types:

• The Option<T> enum can be used when we expect a value, at which point a Some(T) value is given, and a None value is returned when there was no value or in the failure case. In this way Rust forces nothingness to appear in a clear and syntactically identifiable form, leaving no room for null pointer runtime errors.
• The Result<T, E> enum ...