rust-conventions

name	rust-conventions
description	Rust 2021 edition coding conventions. Use when writing or reviewing Rust code.

Rust Conventions

Key decisions and patterns for Rust 2021.

Naming

Type	Convention	Example
Structs/Enums/Traits	PascalCase	UserService, Result
Functions/Variables	snake_case	get_users, user_count
Constants	SCREAMING_SNAKE_CASE	MAX_RETRIES
Modules	snake_case	user_service

Key Decisions

// Getter naming: no get_ prefix
pub fn first(&self) -> &First { &self.first }
pub fn first_mut(&mut self) -> &mut First { &mut self.first }

// Use get_ only for collections
fn get(&self, key: K) -> Option<&V>;

// Conversion prefixes
// as_ → free, borrowed → borrowed
// to_ → expensive, borrowed → owned  
// into_ → consumes self, owned → owned

Error Handling

// Libraries: use thiserror
#[derive(Error, Debug)]
pub enum DataStoreError {
    #[error("data store disconnected")]
    Disconnect(#[from] io::Error),
}

// Applications: use anyhow
fn read_config(path: &Path) -> Result<Config> {
    let contents = fs::read_to_string(path)
        .context("failed to read config")?;
    Ok(parse(&contents)?)
}

// Never use () as error type

Common Pitfalls

// BAD: Mutable borrow conflict
let mut v = vec![1, 2, 3];
let first = &v[0];
v.push(4);  // Error!

// GOOD: Minimize borrow scope
let mut v = vec![1, 2, 3];
let first = v[0];  // Copy, not borrow
v.push(4);

// BAD: Missing lifetime
fn longest(x: &str, y: &str) -> &str

// GOOD: Explicit lifetime
fn longest<'a>(x: &'a str, y: &'a str) -> &'a str

Tools

• Format: cargo fmt
• Lint: cargo clippy -- -D warnings
• Test: cargo test

Testing Pattern

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_parse_valid() {
        let result = parse("test").unwrap();
        assert_eq!(result.value, 42);
    }

    #[test]
    fn test_parse_file() -> Result<()> {
        let content = fs::read_to_string("test.txt")?;
        assert!(parse(&content).is_ok());
        Ok(())
    }
}