macro_rules! impl_entity {
($entity_name:ident) => { ... };
}Expand description
Implements the Entity trait for the given existing type and defines a type alias
of the form MyEntityId = EntityId<MyEntity>. For simple zero-sized types, use the
define_entity! macro instead, which will define the struct and derive all the super traits.
This macro ensures the correct implementation of the Entity trait. The tricky bit is the implementation of
Entity::index, which requires synchronization in multithreaded runtimes. This is an instance of
correctness via macro.