Move run_if to IntoSystem

[DasLixou]

What problem does this solve or what need does it fill?

I am using bevy_eventlistener to listen for events and want to have a run condition on the runned system.
However, run_if is only implemented for IntoSystemConfigs, not IntoSystem, where only pipe and map exist, which both don't really help me.

What solution would you like?

Move / implement run_if for IntoSystem

What alternative(s) have you considered?

Hand-wiring the two systems together.

[alice-i-cecile]

Run conditions still need to work on system sets. If anyone tries their hand at this change, that's the critical requirement that I don't think will be solved by simply moving the method.

[DasLixou]

Rust compiler would nag when both IntoSystemConfigs and IntoSystem had a method called run_if, right? :c

[alice-i-cecile]

Yeah, I think it would likely end up ambiguous, which is no fun at all and would seriously degrade UX. By the way, bevy_eventlistener is largely doomed with #13991 being merged, but we still need run conditions on observers anyways.

[DasLixou]

I guess bevy_mod_picking will also not receive an update using observers because of it's upstreaming? So waiting for 0.15 release it is..?

[alice-i-cecile]

Most likely yeah. Fingers crossed we can get everything in place for 0.15 though!

[DasLixou]

Good news! I could work around it pretty easy by pipeing the bool into my system as an In and returning early

[jnhyatt]

we still need run conditions on observers anyways

Is this the case if we get entity disabling?