parse.rs

#[derive(Debug)]
enum PersonParseError {
    Malformed,
    AgeParseError(std::string::ParseError),
}

impl fmt::Display for PersonParseError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match *self {
            PersonParseError::Malformed => write!(f, "Malformed or empty input string"),
            PersonParseError::AgeParseError(e) => write!(f, "Error parsing age: {}", e),
        }
    }
}


impl Error for PersonParseError {}

impl Person {
    fn from_string(s: &str) -> Result<Person, PersonParseError> {
        let parts = s.split(",");
        let name = parts
            .next()
            .ok_or(Err(PersonParseError::Malformed))?;

        let age = parts
            .next()
            .ok_or(Err(PersonParseError::Malformed))?
            .parse::<usize>().map_err(|e| PersonParseError::AgeParseError(e))?;

        Ok(Person{
            name: name,
            age: age
        })
    }
}
impl From<&str> for Person {
    fn from(s: &str) -> Person {
        Person::from_string(s).unwrap_or_else(Default::default)
    }
}