from actual parameter of type array to formal parameter of list in Ruby
I was curious what * (star) means in front of a method parameter. Here is the result: def xyz(*arr) arr.each do |a| puts a.class end end $xyz 1,2,3 => Fixnum, Fixnum, Fixnum $xyz [1,2,3] => Array $xyz *[1,2,3] => Fixnum, Fixnum, Fixnum Therefore, for example, attribute_names = 'name', 'age', 'phone_number' #creates an array attr_accessor *attribute_names is equivalent to attr_accessor 'name', 'age', 'phone_number'