pub trait ToKeyString: Sized {
// Required method
fn fmt_key_string(&self, f: &mut Formatter<'_>) -> Result;
// Provided method
fn with_key_string<R>(&self, f: impl FnOnce(&str) -> R) -> R { ... }
}Expand description
A trait for converting an attribute key to a string.
Used for performing path comparisons and for constructing error messages when using arbitrary
types as attribute keys. Currently only used by the ParseMetaItem implementations for
BTreeMap and HashMap.
Required Methods§
Sourcefn fmt_key_string(&self, f: &mut Formatter<'_>) -> Result
fn fmt_key_string(&self, f: &mut Formatter<'_>) -> Result
Formats the given value as a key string.
Provided Methods§
Sourcefn with_key_string<R>(&self, f: impl FnOnce(&str) -> R) -> R
fn with_key_string<R>(&self, f: impl FnOnce(&str) -> R) -> R
Runs function f with the key converted to a &str.
Can be specialized by values that can pass a cheaply borrowed &str. The default
implementation calls f with the result from key_to_string.
Dyn Compatibility§
This trait is not dyn compatible.
In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.