Crate easy_cast

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Expand description

Type conversion, success expected

This library exists to make fallible numeric type conversions easy, without resorting to the as keyword.

If you are wondering “why not just use as”, there are a few reasons:

  • integer conversions may silently truncate or sign-extend which does not preserve value
  • prior to Rust 1.45.0 float-to-int conversions were not fully defined; since this version they use saturating conversion (NaN converts to 0)
  • you want some assurance (at least in debug builds) that the conversion will preserve values correctly

Why might you not want to use this library?

  • You want saturating / truncating / other non-value-preserving conversion
  • You want to convert non-numeric types (From supports a lot more conversions than Conv does)!
  • You want a thoroughly tested library (we’re not quite there yet)

Error handling

All traits support two methods:

  • try_* methods return a Result and always fail if the correct conversion is not possible
  • other methods may panic or return incorrect results

In debug builds, methods not returning Result must panic on failure. As with the overflow checks on Rust’s standard integer arithmetic, this is considered a tool for finding logic errors. In release builds, these methods are permitted to return defined but incorrect results similar to the as keyword.

If the always_assert feature flag is set, assertions will be turned on in all builds. Some additional feature flags are available for finer-grained control (see Cargo.toml).

no_std support

When the crate’s default features are disabled (and std is not enabled) then the library supports no_std. In this case, ConvFloat and CastFloat are only available if the libm optional dependency is enabled.




Error types for conversions


Like Into, but for Conv
Like Into, but for ConvFloat
Like From, but supports fallible conversions
Like From, but for approximate numerical conversions
Nearest / floor / ceiling conversions from floating point types

Type Definitions

Result enum with bound Error type