Question

我当时正在用Rust编写一个网络应用程序，想要定义一组函数，这些函数在给定原始字节序列的情况下，可以将其转换为某种结构。 TryFrom特性似乎很合适；但是，当我尝试编译非常基本的示例代码时，我得到的信息却非常微不足道：

#![feature(try_from)]

use std::convert::TryFrom;
use std::io::Read;

#[derive(Debug)]
enum Fruit {
    Apple = 1,
    Orange = 2,
}

impl<T: Read> TryFrom<T> for Fruit {
    type Error = ();

    fn try_from(reader: T) -> Result<Fruit, ()> {
        match reader.bytes().next() {
            Some(x) if x == Fruit::Apple as u8 => Ok(Fruit::Apple),
            Some(x) if x == Fruit::Orange as u8 => Ok(Fruit::Orange),
            _ => Err(())
        }
    }
}

fn main() {
    let bytes = b"\x01";
    let fruit = Fruit::try_from(bytes).unwrap();
    println!("The fruit is: {:?}", fruit);
}

错误是：

Error[E0119]: conflicting implementations of trait `std::convert::TryFrom<_>` for type `Fruit`:
  --> src/main.rs:11:1                                                           
   |                                                                             
11 | impl<T: Read> TryFrom<T> for Fruit {                                        
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^                                          
   |                                                                             
   = note: conflicting implementation in crate `core`:                           
           - impl<T, U> std::convert::TryFrom<U> for T                           
             where T: std::convert::From<U>;

这让我很困惑。有人可以解释这是怎么回事吗？

TryFrom <t>：实现冲突

0 个答案: