# Module std::convert

1.0.0 · source ·
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 (but not generally for all dereferenceable types)
- `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.