| # Error Handling |
| |
| Errors are a fact of life in software, so Rust has a number of features for |
| handling situations in which something goes wrong. In many cases, Rust requires |
| you to acknowledge the possibility of an error and take some action before your |
| code will compile. This requirement makes your program more robust by ensuring |
| that you’ll discover errors and handle them appropriately before deploying your |
| code to production! |
| |
| Rust groups errors into two major categories: _recoverable_ and _unrecoverable_ |
| errors. For a recoverable error, such as a _file not found_ error, we most |
| likely just want to report the problem to the user and retry the operation. |
| Unrecoverable errors are always symptoms of bugs, such as trying to access a |
| location beyond the end of an array, and so we want to immediately stop the |
| program. |
| |
| Most languages don’t distinguish between these two kinds of errors and handle |
| both in the same way, using mechanisms such as exceptions. Rust doesn’t have |
| exceptions. Instead, it has the type `Result<T, E>` for recoverable errors and |
| the `panic!` macro that stops execution when the program encounters an |
| unrecoverable error. This chapter covers calling `panic!` first and then talks |
| about returning `Result<T, E>` values. Additionally, we’ll explore |
| considerations when deciding whether to try to recover from an error or to stop |
| execution. |
