Macro allocative::ident_key

macro_rules! ident_key {
    ($name:ident) => { ... };
}

Create a const of type Key with the provided ident as the value and return that value. This allows the keys to be placed conveniently inline without any performance hit because unlike calling Key::new this is guaranteed to be evaluated at compile time.

The main use case is manual implementations of Allocative, like so:

use allocative::ident_key;
use allocative::Allocative;
use allocative::Visitor;

struct MyStruct {
    foo: usize,
    bar: Vec<()>,
}

impl Allocative for MyStruct {
    fn visit<'a, 'b: 'a>(&self, visitor: &'a mut Visitor<'b>) {
        let mut visitor = visitor.enter_self(self);
        visitor.visit_field(ident_key!(foo), &self.foo);
        visitor.visit_field(ident_key!(bar), &self.bar);
        visitor.exit();
    }
}