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Modify the signature of the request_* methods so that trait_upcasting is not required

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Signed-off-by: Nick Cameron <nrc@ncameron.org>
This commit is contained in:
Nick Cameron 2022-04-07 15:34:36 +01:00
parent bb5db85f74
commit 57d027d23a
2 changed files with 19 additions and 12 deletions
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25
library/core/src/any.rs
View File

@ -110,9 +110,7 @@
//! ## Examples
//!
//! ```
//! # #![allow(incomplete_features)]
//! # #![feature(provide_any)]
//! # #![feature(trait_upcasting)]
//! use std::any::{Provider, Demand, request_ref};
//!
//! // Definition of MyTrait
@ -122,9 +120,9 @@
//!
//! // Methods on `MyTrait` trait objects.
//! impl dyn MyTrait + '_ {
//! /// Common case: get a reference to a field of the error.
//! /// Common case: get a reference to a field of the struct.
//! pub fn get_context_ref<T: ?Sized + 'static>(&self) -> Option<&T> {
//! request_ref::<T>(self)
//! request_ref::<T, _>(self)
//! }
//! }
//!
@ -785,20 +783,29 @@ pub trait Provider {
/// Request a value from the `Provider`.
#[unstable(feature = "provide_any", issue = "none")]
pub fn request_value<'a, T: 'static>(provider: &'a dyn Provider) -> Option<T> {
request_by_type_tag::<'a, tags::Value<T>>(provider)
pub fn request_value<'a, T, P>(provider: &'a P) -> Option<T>
where
T: 'static,
P: Provider + ?Sized,
{
request_by_type_tag::<'a, tags::Value<T>, P>(provider)
}
/// Request a reference from the `Provider`.
#[unstable(feature = "provide_any", issue = "none")]
pub fn request_ref<'a, T: ?Sized + 'static>(provider: &'a dyn Provider) -> Option<&'a T> {
request_by_type_tag::<'a, tags::Ref<tags::MaybeSizedValue<T>>>(provider)
pub fn request_ref<'a, T, P>(provider: &'a P) -> Option<&'a T>
where
T: 'static + ?Sized,
P: Provider + ?Sized,
{
request_by_type_tag::<'a, tags::Ref<tags::MaybeSizedValue<T>>, P>(provider)
}
/// Request a specific value by tag from the `Provider`.
fn request_by_type_tag<'a, I>(provider: &'a dyn Provider) -> Option<I::Reified>
fn request_by_type_tag<'a, I, P>(provider: &'a P) -> Option<I::Reified>
where
I: tags::Type<'a>,
P: Provider + ?Sized,
{
let mut tagged = TaggedOption::<'a, I>(None);
provider.provide(tagged.as_demand());

6
library/core/tests/any.rs
View File

@ -148,7 +148,7 @@ impl Provider for SomeConcreteType {
fn test_provider() {
let obj: &dyn Provider = &SomeConcreteType { some_string: "hello".to_owned() };
assert_eq!(&**request_ref::<String>(obj).unwrap(), "hello");
assert_eq!(&*request_value::<String>(obj).unwrap(), "bye");
assert_eq!(request_value::<u8>(obj), None);
assert_eq!(&**request_ref::<String, _>(obj).unwrap(), "hello");
assert_eq!(&*request_value::<String, _>(obj).unwrap(), "bye");
assert_eq!(request_value::<u8, _>(obj), None);
}