How can I implement custom error types in Rust?

How can I implement custom error types in Rust?

In Rust, you can create custom error types by defining a struct that implements the std::error::Error trait.

Can you show me a simple example of a custom error type?

Sure! Here's a basic example:

#[derive(Debug)]
struct MyError;

impl std::fmt::Display for MyError {
    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
        write!(f, "An error occurred")
    }
}

impl std::error::Error for MyError {}

How do I use this custom error in a function?

You can return your custom error type using the Result type. For example:

fn do_something() -> Result<(), MyError> {
    // some logic
    Err(MyError)
}

What about error handling with this custom type?

You can use pattern matching to handle errors. For instance:

match do_something() {
    Ok(_) => println!("Success!"),
    Err(e) => println!("Error: {}", e),
}