What conditional to use for dynamic sidebar check?

Question

I have looked here on WA and also on the codex but there is no definitive source that I could find.

Which is the proper/best way to check to see if a dynamic_sidebar is active and contains a widget?

I see these 3 solutions at large but not sure what the proper way is:

 1. if(is_active_sidebar('foo')){ //check if the sidebar is active
        dynamic_sidebar('foo');
 }
 2. dynamic_sidebar('foo'); //basically just call it
 3. if(dynamic_sidebar('foo')) //also have seen the inverse if(!dynamic_sidebar('foo') check the return of the function

If they are all valid then why not just choose option 2?

Answer 1

dynamic_sidebar() produces sidebar output. So case by case:

1. Checking if sidebar is active is pointless because otherwise it would just do nothing anyway. This check is useful if you need to perform it elsewhere for something different and/or more extensive than just calling it.

2. Calling it just works. << so this is what you want

3. I am not sure what this is supposed to be, but it is rather pointless. If it works in first half then second half is not called. If it doesn't work in first half second half won't do anything either.