Question

The following code:

class Avalon 
  def h
    puts "petrezselyem"
  end
end
Avalon.new.h

prints out "petrezselyem". However, if I type:

puts Avalon.new.h.size

It gives

undefined method `size' for nil:NilClass (NoMethodError).

Could you please explain this behaviour?

Answer 1

Look at the signature of Kernel#puts:

puts(obj, ...) → nil

This means puts will always return nil and since it’s the last statement in the h method, this will also be the return value of that method.