[Merged by Bors] - Remove the config api

[DJMcNab]

Objective

• Fix the ugliness of the config api.
• Supercedes Add Required system param #2440, Local with required config as a const generic parameter #2463, Local with required config as a type parameter #2491

Solution

• Since [Merged by Bors] - Optional .system #2398, capturing closure systems have worked.
• Use those instead where we needed config before
• Remove the rest of the config api.
• Related: System Lifecycle Rework: all Systems are initialized by definition #2777

[mockersf]

After using config a lot during my latest experiment with Bevy, I grew to dislike it quite a lot...

As it's a useful feature, and config was somewhat discoverable through docs, could you add an example on how to do it without?

[mockersf]

could this example be more complete? you missed a rename here as it's commented

[DJMcNab]

We're stuck in bevy_ecs here, so I can't create an App, without making a stub implementation. That seemed like quite a lot of effort for the example.

There's not really a great way to demonstrate adding systems within bevy_ecs imo, since every consumer should also be using bevy_app.

The rename does need to happen though, thanks.

[mockersf]

After trying to use this way to configure my system, I'm not completely a fan:

fn configured_animate_scale(
    speed: f32,
) -> impl FnMut(Res<Time>, Query<&mut Transform, (With<Text>, With<AnimateScale>)>) {
    move |time, mut query| {
        for mut transform in query.iter_mut() {
            transform.translation = Vec3::new(400.0, 0.0, 0.0);
            transform.scale =
                Vec3::splat((time.seconds_since_startup().sin() as f32 + 1.1) * speed);
        }
    }
}

// Adding this system
app.add_system(configured_animate_scale(5.0))

But still better than the current config api so... 🤷

[cart]

This is also an option. Slightly more typing, but allows you to home the variable type next to the variable name.

fn prepare_system(mut state: LocalFixedTimestepState) -> impl System<In = (), Out = ShouldRun> {
    IntoSystem::into_system(
        move |time: Res<Time>, mut fixed_timesteps: ResMut<FixedTimesteps>| {
            let should_run = state.update(&time);
            if let Some(ref label) = state.label {
                let res_state = fixed_timesteps.fixed_timesteps.get_mut(label).unwrap();
                res_state.step = state.step;
                res_state.accumulator = state.accumulator;
            }

            should_run
        },
    )
}

Or this if you're willing to use deprecated methods 😄

fn prepare_system(mut state: LocalFixedTimestepState) -> impl System<In = (), Out = ShouldRun> {
    (move |time: Res<Time>, mut fixed_timesteps: ResMut<FixedTimesteps>| {
        let should_run = state.update(&time);
        if let Some(ref label) = state.label {
            let res_state = fixed_timesteps.fixed_timesteps.get_mut(label).unwrap();
            res_state.step = state.step;
            res_state.accumulator = state.accumulator;
        }

        should_run
    })
    .system()
}

[cart]

bors r+

[bors]

Pull request successfully merged into main.

Build succeeded:

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