std::mem::discriminant - Rust
Description: API documentation for the Rust `discriminant` fn in crate `std`.
Keywords: rust, rustlang, rust-lang, discriminant

# 1.21.0[−][src]Function std::mem::discriminant

    pub fn discriminant<T>(v: &T) -> Discriminant<T>

Returns a value uniquely identifying the enum variant in `v`.

If `T` is not an enum, calling this function will not result in undefined behavior, but the return value is unspecified.

# Stability

The discriminant of an enum variant may change if the enum definition changes. A discriminant of some variant will not change between compilations with the same compiler.

# Examples

This can be used to compare enums that carry data, while disregarding the actual data:

    use std::mem;

    enum Foo { A(&'static str), B(i32), C(i32) }

    assert_eq!(mem::discriminant(&Foo::A("bar")), mem::discriminant(&Foo::A("baz")));
    assert_eq!(mem::discriminant(&Foo::B(1)), mem::discriminant(&Foo::B(2)));
    assert_ne!(mem::discriminant(&Foo::B(3)), mem::discriminant(&Foo::C(3)));Run