Rust - lesson 6 | HackIndia Skills

Rust - lesson 6 | HackIndia Skills | HackIndia

Example

Add clap

clap is commonly used for parsing command-line arguments. Here is a small setup for a todo-style CLI.

This example keeps the dependency simple. It uses clap with its derive feature.

# Cargo.toml
[package]
name = "rust-todo-cli"
version = "0.1.0"
edition = "2021"

[dependencies]
clap = { version = "4.5", features = ["derive"] }

Example

Use the crate

This code lets your CLI accept an action and a task. The pattern matching is still your code. The crate only handles argument parsing.

Run it with cargo run -- add "pay hostel mess bill".

use clap::{Parser, Subcommand};

#[derive(Parser)]
#[command(name = "todo")]
#[command(about = "A small task CLI")]
struct Cli {
    #[command(subcommand)]
    command: Command,
}

#[derive(Subcommand)]
enum Command {
    Add { task: String },
    Done { id: u32 },
}

fn main() {
    let cli = Cli::parse();

    match cli.command {
        Command::Add { task } => println!("Added task: {task}"),
        Command::Done { id } => println!("Marked task #{id} as done"),
    }
}

Tip

Keep updates controlled

When something breaks after adding a crate, read the first compiler error before changing code. Rust errors usually point to the wrong type, missing import, or missing feature flag.

Use cargo tree when your project feels heavy. It shows all dependency packages pulled in by your crates.

cargo check
cargo tree

Use crates without chaos

One crate, one job

What Cargo does

Choose a crate

Add clap

Use the crate

Do not paste blindly

Keep updates controlled

Do this now

Quick check