What is the relationship between Array and Enumerable?

Question

Array doesn't have sort_by; Enumerable has it. How does this work?

%w[aa aaaa aaa].sort_by{|item| item.length} #=> ['aa','aaa','aaaa']

Doesn't this have to throw an error like undefined method sort_by? What is the relationship between Array and Enumerable?

Answer 1

The Array class includes the Enumerable module. You can see that in the documentation on the left under "Included Modules".