# Function std::error::request_ref

source ·

    pub fn request_ref<T, 'a>(err: &'a (impl Error + ?Sized)) -> Option<&'a T>where
        T: 'static + ?Sized,

🔬This is a nightly-only experimental API. (`error_generic_member_access` #99301)
Expand description

Request a reference of type `T` from the given `impl Error`.

## Examples

Get a string reference from an error.

    use core::error::Error;
    use core::error::request_ref;

    fn get_str(err: &impl Error) -> &str {
        request_ref::<str>(err).unwrap()
    }

Run