Crate castaway

Safe, zero-cost downcasting for limited compile-time specialization.

This crate works fully on stable Rust, and also does not require the standard library. To disable references to the standard library, you must opt-out of the std feature using default-features = false in your Cargo.toml file. When in no-std mode, a separate alloc feature flag is available to support casting to several alloc types not included in core.

Castaway provides the following key macros:

• cast: Attempt to cast the result of an expression into a given concrete type.
• match_type: Match the result of an expression against multiple concrete types.

Macros

• cast
  Attempt to cast the result of an expression into a given concrete type.
• match_type
  Match the result of an expression against multiple concrete types.

Traits

• LifetimeFree
  Marker trait for types that do not contain any lifetime parameters. Such types are safe to cast from non-static type parameters if their types are equal.