Macro value_vtable

macro_rules! value_vtable {
    ($type_name:ty, $type_name_fn:expr) => { ... };
}

Creates a ValueVTable for a given type.

This macro generates a ValueVTable with implementations for various traits (Display, Debug, PartialEq, PartialOrd, Ord, Hash) if they are implemented for the given type.

Arguments

• $type_name:ty - The type for which to create the ValueVTable.
• $type_name_fn:expr - A function that writes the type name to a formatter.

Example

use facet_core::value_vtable;
use core::fmt::{self, Formatter};
use facet_core::TypeNameOpts;

let vtable = value_vtable!(String, |f: &mut Formatter<'_>, _opts: TypeNameOpts| write!(f, "String"));

This cannot be used for a generic type because the impls! thing depends on type bounds. If you have a generic type, you need to do specialization yourself, like we do for slices, arrays, etc. — essentially, this macro is only useful for 1) scalars, 2) inside a derive macro