推荐的 Rust 包

// The `bitflags!` macro generates `struct`s that manage a set of flags.
bitflags! {
    /// Represents a set of flags.
    #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
    struct Flags: u32 {
        /// The value `A`, at bit position `0`.
        const A = 0b00000001;
        /// The value `B`, at bit position `1`.
        const B = 0b00000010;
        /// The value `C`, at bit position `2`.
        const C = 0b00000100;

        /// The combination of `A`, `B`, and `C`.
        const ABC = Self::A.bits() | Self::B.bits() | Self::C.bits();
    }
}

fn main() {
    let e1 = Flags::A | Flags::C;
    let e2 = Flags::B | Flags::C;
    assert_eq!((e1 | e2), Flags::ABC);   // union
    assert_eq!((e1 & e2), Flags::C);     // intersection
    assert_eq!((e1 - e2), Flags::A);     // set difference
    assert_eq!(!e2, Flags::A);           // set complement
}

// 基础
#[derive(new)]
struct Bar {
    a: i32,
    b: String,
}
let _ = Bar::new(42, "Hello".to_owned());

// 根据默认值减少 new 的参数
#[derive(new)]
struct Foo {
    x: bool,
    #[new(value = "42")]
    y: i32,
    #[new(default)]
    z: Vec<String>,
}
let _ = Foo::new(true);

// 支持参数 into
#[derive(new)]
struct Foo {
    #[new(into)]
    x: String,
}
let _ = Foo::new("Hello");

#[derive(new)]
struct Foo {
    #[new(into_iter = "bool")]
    x: Vec<bool>,
}
let _ = Foo::new([true, false]);
let _ = Foo::new(Some(true));

// 支持 enum
#[derive(new)]
enum Enum {
    FirstVariant,
    SecondVariant(bool, #[new(default)] u8),
    ThirdVariant { x: i32, #[new(value = "vec![1]")] y: Vec<u8> }
}
let _ = Enum::new_first_variant();
let _ = Enum::new_second_variant(true);
let _ = Enum::new_third_variant(42);