测试特质对象的相等性

此crate提供了一个DynEq特质，允许比较特质对象。如果两个对象是不同结构体的实例，它们始终不相等。如果它们是同一结构体的实例，将使用该结构体的Eq。

示例

use dyn_eq::DynEq;

trait MyTrait: DynEq {}
dyn_eq::eq_trait_object!(MyTrait);

impl MyTrait for u8 {}
impl MyTrait for u16 {}

let a: &dyn MyTrait = &5u8;
let a_bis: &dyn MyTrait = &5u8;
let b: &dyn MyTrait = &10u8;
let c: &dyn MyTrait = &5u16;
let d: &dyn MyTrait = &10u16;

// Same type, same value
assert!(a == a_bis);
// Same type, different value
assert!(a != b);
// Different type, different value
assert!(a != d);
// Different type, same value
// Even if the value is the same, the fact that it's a diffrent type means it's not equal
assert!(a != c);

// Now data structures containing Box<dyn MyTrait> can derive Eq.
#[derive(PartialEq, Eq)]
struct Container {
    field: Box<dyn MyTrait>
}