为不同包中的类型实现 Serialize 和 Deserialize

Rust 的一致性规则要求你实现特征的特征或类型必须在与 impl 相同的包中定义，因此不可能直接对不同包中的类型实现序列化和反序列化。该 NEWTYPE 模式和 Deref 胁迫提供了一种方法来实现序列化和反序列化该行为的方式为你爱的人同一个类型。

use serde::{Serialize, Serializer, Deserialize, Deserializer};
use std::ops::Deref;

// Pretend this module is from some other crate.
mod not_my_crate {
    pub struct Data { /* ... */ }
}

// This single-element tuple struct is called a newtype struct.
struct Data(not_my_crate::Data);

impl Serialize for Data {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
        where S: Serializer
    {
        // Any implementation of Serialize.
    }
}

impl Deserialize for Data {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
        where D: Deserializer
    {
        // Any implementation of Deserialize.
    }
}

// Enable `Deref` coercion.
impl Deref for Data {
    type Target = not_my_crate::Data;
    fn deref(&self) -> &Self::Target {
        &self.0
    }
}

// Now `Data` can be used in ways that require it to implement
// Serialize and Deserialize.
#[derive(Serialize, Deserialize)]
struct Outer {
    id: u64,
    name: String,
    data: Data,
}