with_children takes a FnMut which prevents some use cases

[HyperLightKitsune]

FnMut prevents transferring ownership.

For example, the following will not compile.

fn spawn(mut commands: Commands, text: String) {
    commands.spawn((0,)).with_children(move |parent| parent.spawn((text,));
}

This is because FnMut can be called multiple times. I believe Commands will only call this function once so it shouldn't be a problem.

This should be a simple change. I'm pretty sure we can just change the input from a FnMut to a FnOnce.

I am completely willing to implement this myself.

[karroffel]

I think you're free to work on it and open a PR! I can assign you so nobody else does duplicate work. If you don't want to/can implement that just let me know and I remove you again as the asignee! 💙

[HyperLightKitsune]

I am sure there are other functions like this (for example for_current_entity). Should I do it for all of them? Should I open different PRs for each one?

[karroffel]

You can rename the PR to something like "Use FnOnce where possible" maybe? That way it works for more cases too.

[HyperLightKitsune]

Ok, will do.