Ruby class_eval method

Question

I'm trying to figure out how to dynamically create methods

class MyClass
  def initialize(dynamic_methods)
    @arr = Array.new(dynamic_methods)
    @arr.each { |m|
      self.class.class_eval do
        def m(*value) 
          puts value
        end
      end
    }
    end
end

tmp = MyClass.new ['method1', 'method2', 'method3']

Unfortunately this only creates the method m but I need to create methods based on the value of m, ideas?

Answer 1

There are two accepted ways:

1. Use define_method:

   @arr.each do |method|
     self.class.class_eval do
       define_method method do |*arguments|
         puts arguments
       end
     end
   end
   

2. Use class_eval with a string argument:

   @arr.each do |method|
     self.class.class_eval <<-EVAL
       def #{method}(*arguments)
         puts arguments
       end
     EVAL
   end
   

The first option converts a closure to a method, the second option evaluates a string (heredoc) and uses regular method binding. The second option has a very slight performance advantage when invoking the methods. The first option is (arguably) a little more readable.

Answer 2

define_method(m) do |*values|
  puts value
end