Create PrimaryKey, etc., derive macro for enums, maybe some other simple types.

[0xForerunner]

Here is an example implementation for an enum. This would lend itself very well to a derive macro.

/// Unique addresses
#[derive(Copy, Display, FromPrimitive)]
#[cw_serde]
pub enum ConfigUnique {
    PriceOracle,
    Market,
    InterestModel,
    WarChest,
    Governance,
    AdminDoubleSig,
    AdminTripleSig,
    Owner,
}

impl<'a> PrimaryKey<'a> for ConfigUnique {
    type Prefix = ();
    type SubPrefix = ();
    type Suffix = Self;
    type SuperSuffix = Self;

    fn key(&self) -> Vec<Key> {
        vec![Key::Val8([*self as u8])]
    }
}

impl KeyDeserialize for ConfigUnique {
    type Output = ConfigUnique;

    #[inline(always)]
    fn from_vec(value: Vec<u8>) -> StdResult<Self::Output> {
        FromPrimitive::from_u8(value[0]).ok_or_else(|| StdError::generic_err("Invalid ConfigUnique"))
    }
}

[0xForerunner]

Another slightly less clean way to accomplish this is

impl<'a, T> PrimaryKey<'a> for T
    where
        T: FromPrimitive
{
    ...
}