Trait ConstDefault 

pub trait ConstDefault: Sized {
    const DEFAULT: Self;
}

Implements a compilation time default value for the implemented type.

Note

Unlike the Default trait implementation the DEFAULT of implementations of this trait can be used in constant evaluation contexts.

Example

const VEC: Vec<u8> = <Vec<u8> as ConstDefault>::DEFAULT;

The above code works while the below code does not:

const VEC: Vec<u8> = <Vec<u8> as Default>::default();

Required Associated Constants

const DEFAULT: Self

The constant default value.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementations on Foreign Types

impl ConstDefault for &&str

const DEFAULT: &&str

impl ConstDefault for &bool

const DEFAULT: &bool

impl ConstDefault for &char

const DEFAULT: &char

impl ConstDefault for &f32

const DEFAULT: &f32

impl ConstDefault for &f64

const DEFAULT: &f64

impl ConstDefault for &i8

const DEFAULT: &i8

impl ConstDefault for &i16

const DEFAULT: &i16

impl ConstDefault for &i32

const DEFAULT: &i32

impl ConstDefault for &i64

const DEFAULT: &i64

impl ConstDefault for &i128

const DEFAULT: &i128

impl ConstDefault for &isize

const DEFAULT: &isize

impl ConstDefault for &str

const DEFAULT: &str = ""

impl ConstDefault for &u8

const DEFAULT: &u8

impl ConstDefault for &u16

const DEFAULT: &u16

impl ConstDefault for &u32

const DEFAULT: &u32

impl ConstDefault for &u64

const DEFAULT: &u64

impl ConstDefault for &u128

const DEFAULT: &u128

impl ConstDefault for &()

const DEFAULT: &()

impl ConstDefault for &usize

const DEFAULT: &usize

impl ConstDefault for bool

const DEFAULT: bool = false

impl ConstDefault for char

const DEFAULT: char = '\0'

impl ConstDefault for f32

const DEFAULT: f32 = 0f32

impl ConstDefault for f64

const DEFAULT: f64 = 0f64

impl ConstDefault for i8

const DEFAULT: i8 = 0i8

impl ConstDefault for i16

const DEFAULT: i16 = 0i16

impl ConstDefault for i32

const DEFAULT: i32 = 0i32

impl ConstDefault for i64

const DEFAULT: i64 = 0i64

impl ConstDefault for i128

const DEFAULT: i128 = 0i128

impl ConstDefault for isize

const DEFAULT: isize = 0isize

impl ConstDefault for u8

const DEFAULT: u8 = 0u8

impl ConstDefault for u16

const DEFAULT: u16 = 0u16

impl ConstDefault for u32

const DEFAULT: u32 = 0u32

impl ConstDefault for u64

const DEFAULT: u64 = 0u64

impl ConstDefault for u128

const DEFAULT: u128 = 0u128

impl ConstDefault for ()

const DEFAULT: () = ()

impl ConstDefault for usize

const DEFAULT: usize = 0usize

impl ConstDefault for PhantomPinned

const DEFAULT: PhantomPinned = Self

impl ConstDefault for AtomicBool

Available on crate feature enable-atomics only.

const DEFAULT: AtomicBool

impl ConstDefault for AtomicI8

Available on crate feature enable-atomics only.

const DEFAULT: AtomicI8

impl ConstDefault for AtomicI16

Available on crate feature enable-atomics only.

const DEFAULT: AtomicI16

impl ConstDefault for AtomicI32

Available on crate feature enable-atomics only.

const DEFAULT: AtomicI32

impl ConstDefault for AtomicI64

Available on crate feature enable-atomics only.

const DEFAULT: AtomicI64

impl ConstDefault for AtomicIsize

Available on crate feature enable-atomics only.

const DEFAULT: AtomicIsize

impl ConstDefault for AtomicU8

Available on crate feature enable-atomics only.

const DEFAULT: AtomicU8

impl ConstDefault for AtomicU16

Available on crate feature enable-atomics only.

const DEFAULT: AtomicU16

impl ConstDefault for AtomicU32

Available on crate feature enable-atomics only.

const DEFAULT: AtomicU32

impl ConstDefault for AtomicU64

Available on crate feature enable-atomics only.

const DEFAULT: AtomicU64

impl ConstDefault for AtomicUsize

Available on crate feature enable-atomics only.

const DEFAULT: AtomicUsize

impl ConstDefault for Duration

const DEFAULT: Duration

impl<'a, T> ConstDefault for &'a [T]

where T: 'a,

const DEFAULT: &'a [T]

impl<A, B, C, D, E, F, G, H, I, J, K, L> ConstDefault for (A, B, C, D, E, F, G, H, I, J, K, L)

where A: ConstDefault, B: ConstDefault, C: ConstDefault, D: ConstDefault, E: ConstDefault, F: ConstDefault, G: ConstDefault, H: ConstDefault, I: ConstDefault, J: ConstDefault, K: ConstDefault, L: ConstDefault,

const DEFAULT: (A, B, C, D, E, F, G, H, I, J, K, L)

impl<B, C, D, E, F, G, H, I, J, K, L> ConstDefault for (B, C, D, E, F, G, H, I, J, K, L)

where B: ConstDefault, C: ConstDefault, D: ConstDefault, E: ConstDefault, F: ConstDefault, G: ConstDefault, H: ConstDefault, I: ConstDefault, J: ConstDefault, K: ConstDefault, L: ConstDefault,

const DEFAULT: (B, C, D, E, F, G, H, I, J, K, L)

impl<C, D, E, F, G, H, I, J, K, L> ConstDefault for (C, D, E, F, G, H, I, J, K, L)

where C: ConstDefault, D: ConstDefault, E: ConstDefault, F: ConstDefault, G: ConstDefault, H: ConstDefault, I: ConstDefault, J: ConstDefault, K: ConstDefault, L: ConstDefault,

const DEFAULT: (C, D, E, F, G, H, I, J, K, L)

impl<D, E, F, G, H, I, J, K, L> ConstDefault for (D, E, F, G, H, I, J, K, L)

where D: ConstDefault, E: ConstDefault, F: ConstDefault, G: ConstDefault, H: ConstDefault, I: ConstDefault, J: ConstDefault, K: ConstDefault, L: ConstDefault,

const DEFAULT: (D, E, F, G, H, I, J, K, L)

impl<E, F, G, H, I, J, K, L> ConstDefault for (E, F, G, H, I, J, K, L)

where E: ConstDefault, F: ConstDefault, G: ConstDefault, H: ConstDefault, I: ConstDefault, J: ConstDefault, K: ConstDefault, L: ConstDefault,

const DEFAULT: (E, F, G, H, I, J, K, L)

impl<F, G, H, I, J, K, L> ConstDefault for (F, G, H, I, J, K, L)

where F: ConstDefault, G: ConstDefault, H: ConstDefault, I: ConstDefault, J: ConstDefault, K: ConstDefault, L: ConstDefault,

const DEFAULT: (F, G, H, I, J, K, L)

impl<G, H, I, J, K, L> ConstDefault for (G, H, I, J, K, L)

where G: ConstDefault, H: ConstDefault, I: ConstDefault, J: ConstDefault, K: ConstDefault, L: ConstDefault,

const DEFAULT: (G, H, I, J, K, L)

impl<H, I, J, K, L> ConstDefault for (H, I, J, K, L)

where H: ConstDefault, I: ConstDefault, J: ConstDefault, K: ConstDefault, L: ConstDefault,

const DEFAULT: (H, I, J, K, L)

impl<I, J, K, L> ConstDefault for (I, J, K, L)

where I: ConstDefault, J: ConstDefault, K: ConstDefault, L: ConstDefault,

const DEFAULT: (I, J, K, L)

impl<J, K, L> ConstDefault for (J, K, L)

where J: ConstDefault, K: ConstDefault, L: ConstDefault,

const DEFAULT: (J, K, L)

impl<K, L> ConstDefault for (K, L)

where K: ConstDefault, L: ConstDefault,

const DEFAULT: (K, L)

impl<L> ConstDefault for (L,)

where L: ConstDefault,

const DEFAULT: (L,)

impl<T> ConstDefault for Option<T>

const DEFAULT: Option<T> = None

impl<T> ConstDefault for *const T

const DEFAULT: *const T

impl<T> ConstDefault for *mut T

const DEFAULT: *mut T

impl<T> ConstDefault for Cell<T>

where T: ConstDefault,

const DEFAULT: Cell<T>

impl<T> ConstDefault for RefCell<T>

where T: ConstDefault,

const DEFAULT: RefCell<T>

impl<T> ConstDefault for UnsafeCell<T>

where T: ConstDefault,

const DEFAULT: UnsafeCell<T>

impl<T> ConstDefault for Empty<T>

const DEFAULT: Empty<T>

impl<T> ConstDefault for PhantomData<T>

where T: ?Sized,

const DEFAULT: PhantomData<T> = Self

impl<T> ConstDefault for ManuallyDrop<T>

where T: ConstDefault,

const DEFAULT: ManuallyDrop<T>

impl<T> ConstDefault for Wrapping<T>

where T: ConstDefault,

const DEFAULT: Wrapping<T>

impl<T> ConstDefault for AtomicPtr<T>

Available on crate feature enable-atomics only.

const DEFAULT: AtomicPtr<T>

impl<T> ConstDefault for MaybeUninit<T>

where T: ConstDefault,

const DEFAULT: MaybeUninit<T>

impl<T, const N: usize> ConstDefault for [T; N]

where T: ConstDefault,

const DEFAULT: [T; N]

Implementors

impl<K: Key, V: ConstDefault> ConstDefault for Assoc<K, V>

where <K::Impl as KeyImpl>::Storage<V>: ConstDefault,

const DEFAULT: Self