Enum Never

pub enum Never {}

Never can never be instantiated. This can be used in places where we want to ensure that no error is returned, such as the ibc_packet_receive entry point.

In contrast to Empty, this does not have a JSON schema and cannot be used for message and query types.

Once the ! type is stable, this is not needed anymore. See https://github.com/rust-lang/rust/issues/35121.

Examples

When using Never in a Result, we can unwrap in a type-safe way:

use cosmwasm_std::Never;

pub fn safe_unwrap<T>(res: Result<T, Never>) -> T {
    match res {
        Ok(value) => value,
        Err(err) => match err {},
    }
}

let res: Result<i32, Never> = Ok(5);
assert_eq!(safe_unwrap(res), 5);

Trait Implementations

impl Debug for Never

fn fmt(&self, _f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for Never

fn fmt(&self, _f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.