Trait std::cmp::Eq  1.0.0[−][src]
pub trait Eq: PartialEq<Self> { }Expand description
Trait for equality comparisons which are equivalence relations.
This means, that in addition to a == b and a != b being strict inverses, the equality must
be (for all a, b and c):
- reflexive: a == a;
- symmetric: a == bimpliesb == a; and
- transitive: a == bandb == cimpliesa == c.
This property cannot be checked by the compiler, and therefore Eq implies
PartialEq, and has no extra methods.
Derivable
This trait can be used with #[derive]. When derived, because Eq has
no extra methods, it is only informing the compiler that this is an
equivalence relation rather than a partial equivalence relation. Note that
the derive strategy requires all fields are Eq, which isn’t
always desired.
How can I implement Eq?
If you cannot use the derive strategy, specify that your type implements
Eq, which has no methods:
enum BookFormat { Paperback, Hardback, Ebook }
struct Book {
    isbn: i32,
    format: BookFormat,
}
impl PartialEq for Book {
    fn eq(&self, other: &Self) -> bool {
        self.isbn == other.isbn
    }
}
impl Eq for Book {}Implementations on Foreign Types
Implementors
impl<A, B, C, D, E, F> Eq for (A, B, C, D, E, F) where
    A: Eq,
    B: Eq,
    C: Eq,
    D: Eq,
    E: Eq,
    F: Eq + ?Sized, 
impl<A, B, C, D, E, F, G> Eq for (A, B, C, D, E, F, G) where
    A: Eq,
    B: Eq,
    C: Eq,
    D: Eq,
    E: Eq,
    F: Eq,
    G: Eq + ?Sized, 
impl<A, B, C, D, E, F, G, H> Eq for (A, B, C, D, E, F, G, H) where
    A: Eq,
    B: Eq,
    C: Eq,
    D: Eq,
    E: Eq,
    F: Eq,
    G: Eq,
    H: Eq + ?Sized, 
impl<A, B, C, D, E, F, G, H, I> Eq for (A, B, C, D, E, F, G, H, I) where
    A: Eq,
    B: Eq,
    C: Eq,
    D: Eq,
    E: Eq,
    F: Eq,
    G: Eq,
    H: Eq,
    I: Eq + ?Sized, 
impl<A, B, C, D, E, F, G, H, I, J> Eq for (A, B, C, D, E, F, G, H, I, J) where
    A: Eq,
    B: Eq,
    C: Eq,
    D: Eq,
    E: Eq,
    F: Eq,
    G: Eq,
    H: Eq,
    I: Eq,
    J: Eq + ?Sized, 
impl<A, B, C, D, E, F, G, H, I, J, K> Eq for (A, B, C, D, E, F, G, H, I, J, K) where
    A: Eq,
    B: Eq,
    C: Eq,
    D: Eq,
    E: Eq,
    F: Eq,
    G: Eq,
    H: Eq,
    I: Eq,
    J: Eq,
    K: Eq + ?Sized, 
impl<A, B, C, D, E, F, G, H, I, J, K, L> Eq for (A, B, C, D, E, F, G, H, I, J, K, L) where
    A: Eq,
    B: Eq,
    C: Eq,
    D: Eq,
    E: Eq,
    F: Eq,
    G: Eq,
    H: Eq,
    I: Eq,
    J: Eq,
    K: Eq,
    L: Eq + ?Sized, 
1.4.0[src]
impl<Ret, A, B, C, D, E, F, G> Eq for unsafe extern "C" fn(A, B, C, D, E, F, G, ...) -> Ret
1.4.0[src]
impl<Ret, A, B, C, D, E, F, G, H> Eq for extern "C" fn(A, B, C, D, E, F, G, H, ...) -> Ret
1.4.0[src]
impl<Ret, A, B, C, D, E, F, G, H> Eq for unsafe extern "C" fn(A, B, C, D, E, F, G, H) -> Ret
1.4.0[src]
impl<Ret, A, B, C, D, E, F, G, H> Eq for unsafe extern "C" fn(A, B, C, D, E, F, G, H, ...) -> Ret
1.4.0[src]
impl<Ret, A, B, C, D, E, F, G, H, I> Eq for extern "C" fn(A, B, C, D, E, F, G, H, I) -> Ret
1.4.0[src]
impl<Ret, A, B, C, D, E, F, G, H, I> Eq for extern "C" fn(A, B, C, D, E, F, G, H, I, ...) -> Ret
1.4.0[src]
impl<Ret, A, B, C, D, E, F, G, H, I> Eq for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I) -> Ret
1.4.0[src]
impl<Ret, A, B, C, D, E, F, G, H, I> Eq for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, ...) -> Ret
1.4.0[src]
impl<Ret, A, B, C, D, E, F, G, H, I, J> Eq for extern "C" fn(A, B, C, D, E, F, G, H, I, J) -> Ret
1.4.0[src]
impl<Ret, A, B, C, D, E, F, G, H, I, J> Eq for extern "C" fn(A, B, C, D, E, F, G, H, I, J, ...) -> Ret
1.4.0[src]
impl<Ret, A, B, C, D, E, F, G, H, I, J> Eq for unsafe fn(A, B, C, D, E, F, G, H, I, J) -> Ret
1.4.0[src]
impl<Ret, A, B, C, D, E, F, G, H, I, J> Eq for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J) -> Ret
1.4.0[src]
impl<Ret, A, B, C, D, E, F, G, H, I, J> Eq for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J, ...) -> Ret
1.4.0[src]
impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Eq for fn(A, B, C, D, E, F, G, H, I, J, K) -> Ret
1.4.0[src]
impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Eq for extern "C" fn(A, B, C, D, E, F, G, H, I, J, K) -> Ret
1.4.0[src]
impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Eq for extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, ...) -> Ret
1.4.0[src]
impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Eq for unsafe fn(A, B, C, D, E, F, G, H, I, J, K) -> Ret
1.4.0[src]
impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Eq for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J, K) -> Ret
1.4.0[src]
impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Eq for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, ...) -> Ret
1.4.0[src]
impl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Eq for fn(A, B, C, D, E, F, G, H, I, J, K, L) -> Ret
1.4.0[src]
impl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Eq for extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, L) -> Ret
1.4.0[src]
impl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Eq for extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, L, ...) -> Ret
1.4.0[src]
impl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Eq for unsafe fn(A, B, C, D, E, F, G, H, I, J, K, L) -> Ret
1.4.0[src]