Trait TidExt

Source

pub trait TidExt<'a>: Tid<'a> {
    // Provided methods
    fn is<T: Tid<'a>>(&self) -> bool { ... }
    fn downcast_ref<'b, T: Tid<'a>>(&'b self) -> Option<&'b T> { ... }
    fn downcast_mut<'b, T: Tid<'a>>(&'b mut self) -> Option<&'b mut T> { ... }
    fn downcast_rc<T: Tid<'a>>(self: Rc<Self>) -> Result<Rc<T>, Rc<Self>> { ... }
    fn downcast_arc<T: Tid<'a>>(self: Arc<Self>) -> Result<Arc<T>, Arc<Self>> { ... }
    fn downcast_box<T: Tid<'a>>(self: Box<Self>) -> Result<Box<T>, Box<Self>> { ... }
    fn downcast_move<T: Tid<'a>>(self) -> Option<T>
       where Self: Sized { ... }
}

Expand description

Extension trait that contains actual downcasting methods.

Use methods from this trait only if dyn Tid was created directly from T for this particular T

If Self is Sized then any of those calls is optimized to no-op because both T and Self are known statically. Useful if you have generic code that you want to behave differently depending on which concrete type replaces type parameter. Usually there are better ways to do this like specialization, but sometimes it can be the only way.