此crate目前依赖于Rust的不可稳定ptr_metadata和unsize功能，并相应地需要一个nightly工具链。

示例

use core::{alloc::Layout, convert::TryFrom, fmt, mem};
use thinnable::*;

const THIN_SIZE: usize = mem::size_of::<&()>();

// Creating a thinnable slice for an array is straightforward.
let thinnable_slice = ThinnableSlice::new([1, 2, 3]);

// Given a thinnable, we can obtain a shared reference...
let r = thinnable_slice.as_thin_ref(); // ThinRef<[u16]>
// ...which is "thin"....
assert_eq!(mem::size_of_val(&r), THIN_SIZE);
// ...but which otherwise behaves just like a regular "fat" DST
// reference
assert_eq!(&r[..2], &[1, 2]);

// For types `M` where the metadata type implements `TryInto<M>`, we
// can use `Thinnable::try_new` to try creating a thinnable using
// `M` as its stored metadata type (dereferencing requires that
// `M: TryInto<R>` where `R` is the original metadata type).
//
// For slices, there's a slightly more ergonomic interface:
let size_default = mem::size_of_val(&thinnable_slice);
let mut thinnable_slice;
thinnable_slice = ThinnableSliceU8::try_slice([1, 2, 3]).unwrap();
let size_u8 = mem::size_of_val(&thinnable_slice);
assert!(size_u8 < size_default);

// We can also obtain a mutable reference...
let mut m = thinnable_slice.as_thin_mut(); // ThinMut<[u16], u8>
// ...which is also "thin"....
assert_eq!(mem::size_of_val(&m), THIN_SIZE);
// ...but which otherwise behaves just like a regular "fat" DST
// reference.
m[1] = 5;
assert_eq!(&m[1..], &[5, 3]);

// We can also have thinnable trait objects:
let thinnable_trait_object;
thinnable_trait_object = Thinnable::<_, dyn fmt::Display>::new(123);
let o = thinnable_trait_object.as_thin_ref();// ThinRef<dyn Display>
assert_eq!(mem::size_of_val(&o), THIN_SIZE);
assert_eq!(o.to_string(), "123");