Trait Into

pub trait Into<T>: Sized {
    // Required method
    fn into(self) -> T;
}

A value-to-value conversion that consumes the input value. The opposite of From.

One should avoid implementing Into and implement From instead. Implementing From automatically provides one with an implementation of Into thanks to the blanket implementation in the standard library.

Prefer using Into over From when specifying trait bounds on a generic function to ensure that types that only implement Into can be used as well.

Note: This trait must not fail. If the conversion can fail, use TryInto.

Generic Implementations

• From<T> for U implies Into<U> for T
• Into is reflexive, which means that Into<T> for T is implemented

Implementing Into for conversions to external types in old versions of Rust

Prior to Rust 1.41, if the destination type was not part of the current crate then you couldn’t implement From directly. For example, take this code:

struct Wrapper<T>(Vec<T>);
impl<T> From<Wrapper<T>> for Vec<T> {
    fn from(w: Wrapper<T>) -> Vec<T> {
        w.0
    }
}

This will fail to compile in older versions of the language because Rust’s orphaning rules used to be a little bit more strict. To bypass this, you could implement