Rust Error Handling

Rust has no exceptions. Instead, Result and Option — explicit, type-safe error handling.

Result and Option¶

use std::fs; fn read_config(path: &str) -> Result { fs::read_to_string(path) } fn find_user(id: u32) -> Option { users.iter().find(|u| u.id == id).cloned() } // ? operator — error propagation fn process() -> Result<(), Box> { let config = fs::read_to_string(“config.toml”)?; let data: Config = toml::from_str(&config)?; Ok(()) }

Custom error types¶

use thiserror::Error;

[derive(Error, Debug)]¶

enum AppError {

[error(“User not found: {0}”)]¶

UserNotFound(u32),

[error(“Database error”)]¶

Database(#[from] sqlx::Error),

[error(“Invalid input: {0}”)]¶

Validation(String), }

Key Takeaway¶

Result for errors, Option for nullable. ? operator for propagation. thiserror for custom error types.