Derive Macro DeriveMessage 

#[derive(DeriveMessage)]

Derive macro that generates a Pod-compatible wire struct from a domain struct.

Given a struct with bool, Option<numeric>, usize/isize, and #[repr(u8)] enum fields, generates {Name}Wire plus From conversions in both directions. Requires the derive feature.

#[derive(photon_ring::DeriveMessage)]
struct Order { price: f64, side: Side, filled: bool, tag: Option<u32> }
// Generates: OrderWire, From<Order> for OrderWire, From<OrderWire> for Order

Derive a Pod-compatible wire struct with From conversions.

Given a struct with fields that may include bool, Option<numeric>, usize/isize, and #[repr(u8)] enums, generates:

1. {Name}Wire — a #[repr(C)] Clone + Copy struct with all fields converted to Pod-safe types, plus unsafe impl Pod.
2. From<Name> for {Name}Wire — converts the domain struct to wire.
3. From<{Name}Wire> for Name — converts the wire struct back.

Field type mappings

Source type	Wire type	To wire	From wire
f32, f64, u8..u128, i8..i128	same	passthrough	passthrough
usize	u64	as u64	as usize
isize	i64	as i64	as isize
bool	u8	if v { 1 } else { 0 }	v != 0
Option<T> (T numeric)	u64	Some(x) => x as u64, None => 0	0 => None, v => Some(v as T)
[T; N] (T: Pod)	same	passthrough	passthrough
Any other type	u8	v as u8	transmute(v)

Enum safety

Enum fields are converted via transmute from u8. The enum must have #[repr(u8)] — the macro emits a compile-time size_of check to enforce this.

Example

#[repr(u8)]
#[derive(Clone, Copy)]
enum Side { Buy = 0, Sell = 1 }

#[derive(photon_ring::Message)]
struct Order {
    price: f64,
    qty: u32,
    side: Side,
    filled: bool,
    tag: Option<u32>,
}
// Generates: OrderWire, From<Order> for OrderWire, From<OrderWire> for Order