Question

我正在编写通过D-Bus与NetworkManager交互的代码，我希望使用enum作为键值，如方案。

例如，我希望一次使用值0作为数字零，并在不同的上下文中使用此Unknown的字符串enum：

pub enum NetworkManagerState {
    Unknown = 0,
    Asleep = 10,
    Disconnected = 20,
    Disconnecting = 30,
    Connecting = 40,
    ConnectedLocal = 50,
    ConnectedSite = 60,
    ConnectedGlobal = 70,
}

最干净，最惯用的方法是什么？有没有办法定义基于元组的枚举，每个条目看起来像(ConnectedSite, 60u32, "Connected")并在上下文中使用每个元组属性。

Answer 1

要将枚举转换为int，您可以使用as i32。
要将i32演示到您的枚举，您可以使用enum_primitive crate：

cargo.toml：

[dependencies]
enum_primitive = "*"

main.rs：

#[macro_use]
extern crate enum_primitive;
use enum_primitive::FromPrimitive;

enum_from_primitive! {
#[derive(Debug, PartialEq)]
pub enum NetworkManagerState {
    Unknown = 0,
    Asleep = 10,
    Disconnected = 20,
    Disconnecting = 30,
    Connecting = 40,
    ConnectedLocal = 50,
    ConnectedSite = 60,
    ConnectedGlobal = 70,
}
}

impl From<i32> for NetworkManagerState {
    fn from(val: i32) -> NetworkManagerState {
        NetworkManagerState::from_i32(val).expect("passed Value does not match an enum value!")
    }
}
impl From<NetworkManagerState> for i32 {
    fn from(val: NetworkManagerState) -> i32 {
        val as i32
    }
}


fn main() {
    let value_i32 = 40;
    let value_enum = NetworkManagerState::Connecting;

    // enum to i32
    println!("{:?}", value_enum as i32);

    // i32 to enum
    println!("{:?}", NetworkManagerState::from_i32(value_i32).unwrap());

    // using from trait
    let y: i32 = NetworkManagerState::Connecting.into();
    println!("{:?}", y);

    // using from trait
    let x: NetworkManagerState = 40.into();
    println!("{:?}", x);
}

使用from trait，您可以让您的函数接受可以转换为枚举的所有内容：

fn fancy_function<T: Into<NetworkManagerState>>(value: T) {
    let internal: NetworkManagerState = value.into();
    println!("{:?}", internal);
}

...

fancy_function(60);
fancy_function(NetworkManagerState::Asleep);

使用Rust的枚举作为双向查找表

1 个答案: