Is there a way to store systems in Vec?

[Nigless]

[bugsweeper]

I think there is no way, because Box is owning, but not shared smartpointer, IntoSystemConfigs takes it by value, so you can't keep it after add_systems, you can just move it.

[bugsweeper]

You can achieve partial goal by keeping specific functions

#[derive(Component, Reflect, Default)]
#[reflect(Component)]
pub struct StandingState;

#[derive(Default)]
pub struct StandingStatePlugin {
    enter: Vec<fn(Commands, Res<AssetServer>) -> ()>,
}

impl Plugin for StandingStatePlugin {
    fn build(&self, app: &mut App) {
        app.register_type::<StandingState>().add_systems(
            PreUpdate,
            (IntoSystem::into_system(self.enter[0]),).in_set(GhostSystems::Enter),
        );
    }
}

[bugsweeper]

That because System can be made from functions and from closures, functions don't keep any values, that is why is clonable, closure can keep not clonable values, that is why it's not clonable.

[NiklasEi]

In bevy_asset_loader I do this with Vec<SystemConfig>.

https://github.com/NiklasEi/bevy_asset_loader/blob/e7c389dec6f51f3a38a66d25367db7010bc743f5/bevy_asset_loader/src/loading_state/config.rs#L88-L97

[bugsweeper]

But you move SystemConfig's into add_systems instead of just keeping it in Vec after add_systems

[Nigless]

I dont need to keep it

[Nigless]

I cant move it out of vector

[NiklasEi]

If you are ok with the vector being empty after the loop, you can use .drain(..) on the vecs like:

for system in self.enter,drain(..) {
    app.add_systems(PreUpdate, system.in_set(StateMachineSystems::Enter));
}