core::convert - Rust
Description: Traits for conversions between types.
Keywords: rust, rustlang, rust-lang, convert

# Module core::convert
1.0.0[−][src]

Expand description

Traits for conversions between types.

The traits in this module provide a way to convert from one type to another type. Each trait serves a different purpose:

- Implement the `AsRef` trait for cheap reference-to-reference conversions
- Implement the `AsMut` trait for cheap mutable-to-mutable conversions
- Implement the `From` trait for consuming value-to-value conversions
- Implement the `Into` trait for consuming value-to-value conversions to types outside the current crate
- The `TryFrom` and `TryInto` traits behave like `From` and `Into`, but should be implemented when the conversion can fail.

The traits in this module are often used as trait bounds for generic functions such that to arguments of multiple types are supported. See the documentation of each trait for examples.

As a library author, you should always prefer implementing `From<T>` or `TryFrom<T>` rather than `Into<U>` or `TryInto<U>`, as `From` and `TryFrom` provide greater flexibility and offer equivalent `Into` or `TryInto` implementations for free, thanks to a blanket implementation in the standard library. When targeting a version prior to Rust 1.41, it may be necessary to implement `Into` or `TryInto` directly when converting to a type outside the current crate.

# Generic Implementations

- `AsRef` and `AsMut` auto-dereference if the inner type is a reference
- `From``<U> for T` implies `Into``<T> for U`
- `TryFrom``<U> for T` implies `TryInto``<T> for U`
- `From` and `Into` are reflexive, which means that all types can `into` themselves and `from` themselves

See each trait for usage examples.

## Enums

Infallible

The error type for errors that can never happen.

## Traits

FloatToInt Experimental

Supporting trait for inherent methods of `f32` and `f64` such as `to_int_unchecked`. Typically doesn’t need to be used directly.

AsMut

Used to do a cheap mutable-to-mutable reference conversion.

AsRef

Used to do a cheap reference-to-reference conversion.

From

Used to do value-to-value conversions while consuming the input value. It is the reciprocal of `Into`.

Into

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

TryFrom

Simple and safe type conversions that may fail in a controlled way under some circumstances. It is the reciprocal of `TryInto`.

TryInto

An attempted conversion that consumes `self`, which may or may not be expensive.

## Functions

identity

The identity function.