Deleting items from an array requires multiple passes to remove them all

Question

I have an array of ~1200 ruby objects and I want to loop over them and delete the ones with names that contain words or parts of words.

So I tried this:

Answer 1

That's you modifying underlying collection while iterating over it.
Basically, if collection changes in some way during iteration (becomes empty, gets prepended with a new element, etc), iterator doesn't have a lot of ways to handle it.

Try reject instead.

list.reject! {|item| item.name =~ /cat|dog|rat/i }