[−][src]Crate macro_attr_2018
This crate provides the macro_attr!
macro that enables the use of custom, macro-based attributes and derivations.
The macro_attr!
macro should be used to wrap an entire single item (enum
, struct
, etc.) declaration, including its attributes (both derive
and others). All attributes and derivations which whose names end with !
will be assumed to be implemented by macros, and treated accordingly.
use macro_attr_2018::macro_attr; // Define some traits to be derived. trait TypeName { fn type_name() -> &'static str; } trait ReprType { type Repr; } // Define macros which derive implementations of these macros. macro_rules! TypeName { // We can support any kind of item we want. (() $vis:vis enum $name:ident $($tail:tt)+) => { TypeName! { @impl $name } }; (() $vis:vis struct $name:ident $($tail:tt)+) => { TypeName! { @impl $name } }; // Inner rule to cut down on repetition. (@impl $name:ident) => { impl TypeName for $name { fn type_name() -> &'static str { stringify!($name) } } }; } macro_rules! ReprType { // Note that we use a "derivation argument" here for the `$repr` type. (($repr:ty) $vis:vis enum $name:ident $($tail:tt)+) => { impl ReprType for $name { type Repr = $repr; } }; }
Macros
macro_attr | When given an item definition, including its attributes, this macro parses said attributes and dispatches any attributes or derivations suffixed with |