Question

Is there a one-line way to use include if the array it’s searching may not be assigned?

I’ve tried a lot of variants of

(foo || []).include?(:bar)

but without success

Answer 1

If foo really is nil, as opposed to undefined, then (foo || []).include?(:bar) will do what you want, however if foo is not set to anything yet, then you will get a NameError so we can check for that with a longer oneliner…

defined?(foo) ? (foo || []).include?(:bar) : false