Trait icu_provider::DynamicDataMarker

source ·

pub trait DynamicDataMarker: 'static {
    type DataStruct: for<'a> Yokeable<'a>;
}

Expand description

Trait marker for data structs. All types delivered by the data provider must be associated with something implementing this trait.

Structs implementing this trait are normally generated with the data_struct macro.

By convention, the non-standard Marker suffix is used by types implementing DynamicDataMarker.

In addition to a marker type implementing DynamicDataMarker, the following impls must also be present for the data struct:

impl<'a> Yokeable<'a> (required)
impl ZeroFrom<Self>

Also see DataMarker.

Note: DynamicDataMarkers are quasi-const-generic compile-time objects, and as such are expected to be unit structs. As this is not something that can be enforced by the type system, we currently only have a 'static bound on them (which is needed by a lot of our code).

§Examples

Manually implementing DynamicDataMarker for a custom type:

use icu_provider::prelude::*;
use std::borrow::Cow;

#[derive(yoke::Yokeable, zerofrom::ZeroFrom)]
struct MyDataStruct<'data> {
    message: Cow<'data, str>,
}

struct MyDataStructMarker;

impl DynamicDataMarker for MyDataStructMarker {
    type DataStruct = MyDataStruct<'static>;
}

// We can now use MyDataStruct with DataProvider:
let s = MyDataStruct {
    message: Cow::Owned("Hello World".into()),
};
let payload = DataPayload::<MyDataStructMarker>::from_owned(s);
assert_eq!(payload.get().message, "Hello World");