在编译时为类型生成唯一ID

Question

我想在编译时为每种类型生成一个唯一的id.这可能在Rust吗？

到目前为止,我有以下代码

//Pseudo code
struct ClassTypeId{
    id: &'static uint
}
impl ClassTypeId{
    fn get_type<T>(&mut self) -> &'static uint {
        let _id :&'static uint = self.id + 1;
        self.id = _id;
        _id
    }
}

let c = ClassTypeId{id:0};
c.get_type::<i32>();  // returns 1
c.get_type::<f32>();  // returns 2
c.get_type::<i32>();  // returns 1
c.get_type::<uint>(); // returns 3

我从C++库中偷走了这个想法,看起来像这样

typedef std::size_t TypeId;

        template <typename TBase>
        class ClassTypeId
        {
        public:

            template <typename T>
            static TypeId GetTypeId()
            {
                static const TypeId id = m_nextTypeId++;
                return id;
            }

        private:

            static TypeId m_nextTypeId;
        };

        template <typename TBase>
        TypeId ClassTypeId<TBase>::m_nextTypeId = 0;
    }

Answer 1

std::any::TypeId 做那样的事情:

use std::any::TypeId;

fn main() {
    let type_id = TypeId::of::<isize>();
    println!("{:?}", type_id);
}

输出:

TypeId { t: 4150853580804116396 }

Answer 2

这听起来像是bitflags的工作!宏:

#[macro_use] extern crate rustc_bitflags;

bitflags!(
    #[derive(Debug)]
    flags ComponentMask: u8 {
        const Render     = 0b00000001,
        const Position   = 0b00000010,
        const Physics    = 0b00000100
    }
);

// the set of components owned by an entity:
let owned_components:  = Render | Position;

// check whether an entity has a certain component:
if owned_components.contains(Physics) { ... }

http://doc.rust-lang.org/rustc_bitflags/macro.bitflags!.html