Struct abi_stable::type_level::downcasting::TD_CanDowncast

pub struct TD_CanDowncast;

Passed to trait object constructors to make the trait object downcast capable, as opposed to TD_Opaque.

The from_value/from_ptr/from_const methods here take this type.

Example

use abi_stable::{
    sabi_trait::doc_examples::Action_TO,
    std_types::RBox,
    type_level::downcasting::TD_CanDowncast,
};

// The type annotation is purely for the reader.
let mut object: Action_TO<'static, RBox<()>> =
    Action_TO::from_value(100_usize, TD_CanDowncast);

assert_eq!(object.obj.downcast_as::<u8>().ok(), None);
assert_eq!(object.obj.downcast_as::<char>().ok(), None);
assert_eq!(object.obj.downcast_as::<usize>().ok(), Some(&100_usize));

Trait Implementations

impl Clone for TD_CanDowncast

fn clone(&self) -> TD_CanDowncast

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T> GetUTID<T> for TD_CanDowncast

where T: 'static,

const UID: extern "C" fn() -> MaybeCmp<UTypeId> = _

the function.

impl Copy for TD_CanDowncast