Ruby minus operator with ActiveRecord objects

Question

Can you explain pls, how's Ruby's minus operator working? Not just trivial case like 5 - 2. A bit more complex – we have 2 arrays with ActiveRecord objects: Array A = User.where(...), Array B = User.where(...), I wanna make A - B, how is it working? Is it just comparing objects IDs, or all attributes, or smth else?

Answer 1

Is it just comparing objects IDs?

Type and ID, yes.

pry(main)> show-source User#eql?

From: /Users/sergio/.gem/ruby/2.5.1/gems/activerecord-5.2.0/lib/active_record/core.rb @ line 420:
Owner: ActiveRecord::Core
Visibility: public
Number of lines: 6

def ==(comparison_object)
  super ||
    comparison_object.instance_of?(self.class) &&
    !id.nil? &&
    comparison_object.id == id
end