# Bevy Discovery

This crate adds `#[derive(DiscoveryPlugin)]` which will scan the project files for
functions annotated with `#[system]` and register them automagically.
Example:

```rust
use bevy::prelude::*;

#[macro_use]
extern crate bevy_discovery;

fn main() {
    App::build()
        .add_plugin(DiscoveryPlugin)
        .run();
}

#[system]
fn discovered_system() {
    println!("Woo, discovered system!");
}

#[system(stage::POST_UPDATE)]
fn post_update_system() {
    println!("Hey, post update system!");
}

#[derive(DiscoveryPlugin)]
struct DiscoveryPlugin;
```

## Compile time performance

<table>
    <tr>
        <td></td>
        <td>Full rebuild</td>
        <td>Incremental</td>
    </tr>
    <tr>
        <td>Normal</td>
        <td>198.982 ± 1.167 s</td>
        <td>25.944 ± 1.486 s</td>
    </tr>
    <tr>
        <td>Discovered</td>
        <td>207.636 ± 3.785 s</td>
        <td>26.546 ± 1.782 s</td>
    </tr>
</table>

These are the compile times for [my fork of bevy-robbo](https://github.com/TheRawMeatball/bevy-robbo),
averaged over five runs with a discarded warmup round each using [hyperfine](https://github.com/sharkdp/hyperfine).