如何为我的类型实现 String::from？

Question

我有一个类型Clock：

#[derive(Debug, PartialEq)]
pub struct Clock {
    hours: i32,
    minutes: i32,
}

为此实现了一些特征。例如：

#[allow(clippy::match_bool)]
impl fmt::Display for Clock {
    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
        let tmp = match (self.hours < 10, self.minutes < 10) {
            (false, false) => ("", self.hours, "", self.minutes),
            (false, true) => ("", self.hours, "0", self.minutes),
            (true, false) => ("0", self.hours, "", self.minutes),
            (true, true) => ("0", self.hours, "0", self.minutes),
        };
        write!(
            formatter,
            "{}",
            format!("{}{}:{}{}", tmp.0, tmp.1, tmp.2, tmp.3)
        )
    }
}

我想实现String::from(Clock::new(...))。我该怎么做？

我尝试过：

impl convert::From<Clock> for String {
    fn from(clock: Clock) -> String {
        clock.to_string()
    }
}

Answer 1

可行的解决方案：

impl From<Clock> for String {
    fn from(clock: Clock) -> String {
        clock.to_string()
    }
}

impl fmt::Display for Clock {
    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
        write!(
            formatter,
            "{}",
            format!("{:02}:{:02}", self.hours, self.minutes)
        )
    }
}