Attribute Macro machine 

#[machine]

Define a typed machine that carries durable context across states.

The machine must be a struct whose first generic parameter is the #[state] enum family:

• struct Task<TaskState> { ... }
• struct Payment<PaymentState> { ... }

#[machine] generates:

• the typed Machine<State> surface
• a builder for new machines
• a machine-scoped machine::State enum for matching rebuilt machines
• a machine-scoped machine::Fields struct for heterogeneous batch rebuilds

If you need derives, place them below #[machine].

use statum::{machine, state};

#[state]
enum TaskState {
    Draft,
    Published,
}

#[machine]
struct Task<TaskState> {
    id: u64,
}

fn main() {
    let task = Task::<Draft>::builder().id(1).build();
    assert_eq!(task.id, 1);
}

Define a typed machine that carries durable context across states.

Apply #[machine] to a struct whose first generic parameter is the #[state] enum family. Statum generates the typed machine surface, builders, the machine-scoped machine::State enum, and helper items such as machine::Fields for heterogeneous batch rebuilds.