Probar Derive Macros: Type-Safe ECS Selectors (Poka-Yoke)

Per spec Section 4: This crate provides derive macros that eliminate "stringly-typed" selectors, making it impossible to write invalid entity or component queries at compile time.

Toyota Way: Poka-Yoke (Mistake-Proofing)

Instead of runtime errors from typos:

// BAD: Stringly-typed, prone to typos (runtime error)
let player = game.entity("playr");  // Typo! Runtime panic

Use compile-time checked selectors:

// GOOD: Type-safe, compile-time checked (Poka-Yoke)
#[derive(ProbarEntity)]
struct Player;

let player = game.entity::<Player>();  // Compile error if wrong

Available Macros

• [ProbarEntity] - Derive for entity type markers
• [ProbarComponent] - Derive for component type inspection
• [ProbarSelector] - Generate type-safe selector enums

Example

use probar_derive::{ProbarEntity, ProbarComponent, ProbarSelector};

// Define entity markers
#[derive(ProbarEntity)]
#[probar(name = "player")]
struct Player;

#[derive(ProbarEntity)]
#[probar(name = "enemy")]
struct Enemy;

// Define components
#[derive(ProbarComponent)]
struct Position {
    x: f32,
    y: f32,
}

#[derive(ProbarComponent)]
struct Health {
    current: u32,
    max: u32,
}

// Generate selector enum
#[derive(ProbarSelector)]
#[probar(entities = [Player, Enemy])]
#[probar(components = [Position, Health])]
struct GameSelectors;

// Usage in tests (compile-time safe!)
async fn test_player_movement() {
    let game = StateBridge::new();

    // Type-safe entity access
    let player = game.entity::<Player>().await?;

    // Type-safe component access
    let pos: Position = game.component::<Position>(player)?;

    assert!(pos.x > 0.0);
}