Trait alloc::slice::Concat

pub trait Concat<Item: ?Sized> {
    type Output;

    // Required method
    fn concat(slice: &Self) -> Self::Output;
}

🔬This is a nightly-only experimental API. (slice_concat_trait #27747)

Helper trait for [T]::concat.

Note: the Item type parameter is not used in this trait, but it allows impls to be more generic. Without it, we get this error:

error[E0207]: the type parameter `T` is not constrained by the impl trait, self type, or predica
   --> library/alloc/src/slice.rs:608:6
    |
608 | impl<T: Clone, V: Borrow<[T]>> Concat for [V] {
    |      ^ unconstrained type parameter

This is because there could exist V types with multiple Borrow<[_]> impls, such that multiple T types would apply:

pub struct Foo(Vec<u32>, Vec<String>);

impl std::borrow::Borrow<[u32]> for Foo {
    fn borrow(&self) -> &[u32] { &self.0 }
}

impl std::borrow::Borrow<[String]> for Foo {
    fn borrow(&self) -> &[String] { &self.1 }
}

Required Associated Types

type Output

🔬This is a nightly-only experimental API. (slice_concat_trait #27747)

The resulting type after concatenation

Required Methods

fn concat(slice: &Self) -> Self::Output

🔬This is a nightly-only experimental API. (slice_concat_trait #27747)

Implementation of [T]::concat

Object Safety

This trait is not object safe.

Implementors

impl<S: Borrow<str>> Concat<str> for [S]

Note: str in Concat<str> is not meaningful here. This type parameter of the trait only exists to enable another impl.

type Output = String

impl<T: Clone, V: Borrow<[T]>> Concat<T> for [V]

type Output = Vec<T>