Using local variables in define_method

Question

I would like to understand how define_method works and how to properly use the variables outside of the definition block. Here is my code:

class         


        

Answer 1

As mentionned in comments this is down to closures - the block passed to define_method captures the local variables from its scope (and not just their value as you found out).

for doesn't create a new scope, so your method 'sees' the change to i. If you use a block (for example with each) then a new scope is created and this won't happen. You just need to change your code to

class Test
  def self.plugin
    (1..2).each do |i|
      define_method("test#{i}".to_sym) do
        p i
      end
    end
  end
  plugin
end

which is basically what the question linked by Arup was about