Wrapper

amplify_derive

Derive Macro Wrapper 

Source 
#[derive(Wrapper)]
{
    // Attributes available to this derive:
    #[wrap]
    #[wrapper]
    #[amplify_crate]
}
Expand description

Creates rust new type wrapping existing type. Can be used in structures containing multiple named or unnamed fields; in this case the field you’d like to wrap should be marked with #[wrap] attribute; otherwise the first field is assumed to be the wrapped one.

NB: You have to use derive(From) in order foe Wrapper to work properly. Also, in case of multiple fields, each non-wrapped field type must implement Default trait.

Supports automatic implementation of the following traits:

You can implement additional derives, it they are implemented for the wrapped type, using #[wrapper()] proc macro:

  1. Reference access to the inner type:
  2. Formatting:
  3. Indexed access to the inner type:
  4. Arithmetic operations:
  5. Boolean and bit-wise operations:

There are shortcuts for derivations:

  • #[wrapper(Hex)] will derive both LowerHex, UpperHex and FromHex;
  • #[wrapper(Exp)] will derive both LowerExp and UpperExp;
  • #[wrapper(NumberFmt)] will derive all number formatting traits (LowerHex, UpperHex, LowerExp, UpperExp, Octal);
  • #[wrapper(RangeOps)] will derive all index traits working with ranges (IndexRange, IndexTo, IndexFrom, IndexInclusive, IndexToInclusive, IndexFull);
  • #[wrapper(MathOps)] will derive all arithmetic operations (Neg, Add, Sub, Mul, Div, Rem);
  • #[wrapper(BoolOps)] will derive all boolean operations (Not, BitAnd, BitOr, BitXor);
  • #[wrapper(BitOps)] will derive all boolean operations and bit shifts (Not, BitAnd, BitOr, BitXor, Shl, Shr).

Other traits, such as PartialEq, Eq, PartialOrd, Ord, Hash can be implemented using standard #[derive] attribute in the same manner as Default, Debug and From

§Example

Simple wrapper:

use amplify::Wrapper;

#[derive(Wrapper, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Default, From, Debug, Display)]
#[display(inner)]
#[wrapper(LowerHex, UpperHex, Octal)]
#[wrapper(MathOps, BitOps)]
struct Int64(i64);

More complex wrapper with multiple unnamed fields:

use std::marker::PhantomData;

use amplify::Wrapper;

#[derive(Clone, Wrapper, Default, From)]
#[wrapper(Debug)]
struct Wrapped<T, U>(
    #[wrap]
    #[from]
    HashMap<usize, Vec<U>>,
    PhantomData<T>,
)
where U: Sized + Clone + Debug;

let w = Wrapped::<(), u8>::default();
assert_eq!(w.into_inner(), HashMap::<usize, Vec<u8>>::default());

Wrappers for indexable types

use amplify::Wrapper;

#[derive(Wrapper, From)]
#[wrapper(Index, RangeOps)]
struct VecNewtype(Vec<u8>);