Trait UnwrappedAs

pub trait UnwrappedAs {
    // Required method
    fn unwrapped_as<Dst>(self) -> Dst
       where Self: UnwrappedCast<Dst>;
}

Used to cast values, panicking if the value does not fit.

This is a convenience trait to enable writing src.unwrapped_as::<Dst>(). This would not work with the UnwrappedCast::unwrapped_cast method because the UnwrappedCast trait is generic while its UnwrappedCast::unwrapped_cast method is not generic.

This trait’s method is suitable for chaining.

If there is an implementation of UnwrappedCast<Dst> for &Src but not for Src, and the variable src is of type Src, then src.unwrapped_as::<Dst>() would not work and (&src).unwrapped_as::<Dst>() is not easy to use with chaining, but src.borrow().unwrapped_as::<Dst>() works.

Panics

This trait’s method panics if the value does not fit in the destination, even when debug assertions are not enabled.

Examples

use az::UnwrappedAs;
assert_eq!(5i32.unwrapped_as::<u32>(), 5);
assert_eq!(17.1f32.unwrapped_as::<u8>(), 17);

The following panics because of overflow.

use az::UnwrappedAs;
let _overflow = (-5i32).unwrapped_as::<u32>();

The following example shows how this trait can be used when UnwrappedCast is implemented for a reference type.

use az::{UnwrappedAs, UnwrappedCast};
use core::borrow::Borrow;
struct I(i32);
impl UnwrappedCast<i64> for &'_ I {
    fn unwrapped_cast(self) -> i64 { self.0.unwrapped_cast() }
}

let r = &I(-5);
assert_eq!(r.unwrapped_as::<i64>(), -5);
let owned = I(12);
assert_eq!(owned.borrow().unwrapped_as::<i64>(), 12);

Required Methods

fn unwrapped_as<Dst>(self) -> Dst

where Self: UnwrappedCast<Dst>,

Casts the value.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors

impl<T> UnwrappedAs for T