Rust code shared from the playground

playground.rs

#[macro_use]
extern crate serde_derive;
extern crate toml;

use std::fs::File;
use std::io::Read;

#[derive(Debug, Serialize, Deserialize)]
pub struct Config<'a> {
    target: &'a str,
    email: &'a str,
    passwd: &'a str,
    #[serde(default)]
    smtp: &'a str,
}

fn main() {
    let mut file = File::open("foo").expect("Failed to open configuration file");
    let mut cfgstr = String::new();
    file.read_to_string(&mut cfgstr).expect(
        "Failed to read the configuration file",
    );
    let mut config: Config = toml::from_str(&cfgstr).expect("Failed to load configuration");

    // TODO add some more robust default value handling
    if config.smtp == "" {
        let mut s = config.email.split('@').skip(1);
        let domain = s.next().expect("Invalid e-mail format: no domain");
        let smtp = "smtp.".to_owned() + domain;
        println!("Assuming smtp server: {}", smtp);
        config.smtp = &smtp;
    }

    // do something
}