[−][src]Trait primitive_from::PrimitiveFrom
A generic interface for casting between machine scalars with the
as operator, which admits narrowing and precision loss.
Implementers of this trait PrimitiveFrom should behave like a primitive
numeric type (e.g. a newtype around another primitive), and the
intended conversion must never fail.
Examples
let three: i32 = PrimitiveFrom::from(3.14159265f32); assert_eq!(three, 3);
Safety
Currently, some uses of the as operator are not entirely safe.
In particular, it is undefined behavior if:
- A truncated floating point value cannot fit in the target integer type (#10184);
ⓘThis example is not tested
let x: u8 = PrimitiveFrom::from(1.04E+17); // UB
- Or a floating point value does not fit in another floating point type (#15536).
ⓘThis example is not tested
let x: f32 = PrimitiveFrom::from(1e300f64); // UB