Module core::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
  • 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.


The error type for errors that can never happen.



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

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

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

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

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

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

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


The identity function.