Macro root

macro_rules! root {
    ($ident:ident, $cx:ident) => { ... };
    ($ident:ident, init($init:expr), $cx:ident) => { ... };
    ($ident:ident, new($path:tt$(<$ty:ty>)?), $cx:ident) => { ... };
    ($ident:ident, $value:expr, $cx:ident) => { ... };
    (@ $ident:ident, $value:expr, $cx:ident) => { ... };
}

Creates a new root that will be traced during garbage collection. The value returned by this macro is no longer bound to the Context and so can be used outside of the Context’s lifetime. The root is tied to the stack, and will be unrooted when it goes out of scope.