Crate type_val

This crate allows for the creation of type-level values. Any value can be type-level as long as it can be initialized as a constant. All type-level values implement the TypeVal trait, and so can be provided as type parameters.

Example

#[macro_use]
extern crate type_val;
use type_val::TypeVal;

use std::marker::PhantomData;

fn main() {
    let mut adder = Adder::<Two, One>::new();
    
    assert_eq!(adder.sum, 2);
    
    adder.add();
    
    assert_eq!(adder.sum, 3);
}

def_type_val! {
    type One: u32 = 1;
    type Two: u32 = 2;
}

struct Adder<S, I> {
    sum: u32,
    _marker: PhantomData<(S, I)>,
}

impl <S, I> Adder<S, I>
    where S: TypeVal<u32>,
          I: TypeVal<u32>,
{
    fn new() -> Adder<S, I> {
        Adder {
            // Get the value of S
            sum: S::VAL,
            _marker: PhantomData,
        }
    }
    
    fn add(&mut self) {
        // Get the value of I
        self.sum += I::VAL;
    }
}

!

Macros

def_type_val

This macro is used to implement the TypeVal trait. Any number of values can be initialized with a single invocation. Items prefixed by pub are public. Attributes to be applied to items in a block, including doc comments, should go above their targets.

Traits

TypeVal

A trait implemented by type-level values.