Struct std::any::Demand

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#[repr(transparent)]
pub struct Demand<'a>(_);

🔬This is a nightly-only experimental API. (provide_any #96024)

Expand description

A helper object for providing data by type.

A data provider provides values by calling this type’s provide methods.

Implementations

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impl<'a> Demand<'a>

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pub fn provide_value<T>(&mut self, fulfil: impl FnOnce() -> T) -> &mut Demand<'a> where
T: 'static,

🔬This is a nightly-only experimental API. (provide_any #96024)

Provide a value or other type with only static lifetimes.

Examples

Provides a String by cloning.

use std::any::{Provider, Demand};

impl Provider for SomeConcreteType {
    fn provide<'a>(&'a self, demand: &mut Demand<'a>) {
        demand.provide_value::<String>(|| self.field.clone());
    }
}

Run

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pub fn provide_ref<T>(&mut self, value: &'a T) -> &mut Demand<'a> where
T: 'static + ?Sized,

🔬This is a nightly-only experimental API. (provide_any #96024)

Provide a reference, note that the referee type must be bounded by 'static, but may be unsized.

Examples

Provides a reference to a field as a &str.

use std::any::{Provider, Demand};

impl Provider for SomeConcreteType {
    fn provide<'a>(&'a self, demand: &mut Demand<'a>) {
        demand.provide_ref::<str>(&self.field);
    }
}

Run