Error Handling

Error handling in Rust is very different from Perl. Rust has no null value like Perl's undef. Rust doesn't really have exceptions either, though we can panic! which terminates safely and unwinds the stack. Instead, Rust leverages its type system to create two very common enumerations: Option and Result.

Option

An option is either Some, and has some data, or it is None, and has no data.

#![allow(unused_variables)]
fn main() {
pub enum Option<T> {
    Some(T),
    None,
}
}

Since we can have all sorts of optional types, we use a generic type T. An option is either type Some(T), in which case our data is of type T, or it is type None and there is no data.

Result

A result is either Ok, and has some good data, or it is Err, and has some error data.

#![allow(unused_variables)]
fn main() {
pub enum Result<T, E> {
    Ok(T),
    Err(E),
}
}

Now there are two generic types, good data of type T and error data of type E.