my-first-cli-tool

• Learn from https://github.com/rust-cli/book

Have Learned

• BufReader is a better choise than read_to_string
• Instead of the panic!, we can also easily write return

let result = std::fs::read_to_string("test.txt");
let content = match result {
    Ok(content) => { content },
    Err(error) => { return Err(error.into()); }
};

• unwrap() is a shortcut for the match with panic!
• Box<dyn std::error::Error>: It’s a Box that can contain any type that implements the standard Error trait. All errors can be put into this box

fn main() -> Result<(), Box<dyn std::error::Error>> {
    // `?` expands to code that converts error types and returns error
    let content = std::fs::read_to_string("test.txt")?;
    println!("file content: {}", content);
    Ok(())
}

• println! tells the system to flush to the terminal every time (from buffer to terminal)
• By convention, cargo will look for integration tests in the tests/ directory.

References

• Crate clap