Various styles of nested method definitions

nested-tags-exploration.rb

class NestedMethods
  def bad
    def inner
      puts "bad/inner"
    end
    inner
  end

  def good_lambda
    inner = -> { puts "good_lambda/inner" }
    inner.call
  end

  def good_eigen
    class << self
      def inner
        puts "good_eigen/inner"
      end
    end
    inner
  end

  def good_ceval
    self.class_eval do
      def inner
        puts "good_ceval/inner"
      end
    end
    inner
  end

  def good_mexec
    self.module_exec do
      def inner
        puts "good_mexec/inner"
      end
    end
    inner
  end
end

nm = NestedMethods.new

nm.bad
nm.inner rescue nil
nm.good_lambda
nm.inner rescue nil
nm.good_eigen
nm.inner rescue nil
nm.good_ceval
nm.inner rescue nil
nm.good_mexec
nm.inner rescue nil

def toplevel_bad
  def inner
    puts "toplevel_bad/inner"
  end
  inner
end

def toplevel_good_lambda
  inner = -> { puts "toplevel_good_lambda/inner" }
  inner.call
end

def toplevel_good_eigen
  class << self
    def inner
      puts "toplevel_good_eigen/inner"
    end
  end
  inner
end

def toplevel_good_ceval
  self.class_eval do
    def inner
      puts "toplevel_good_ceval/inner"
    end
  end
  inner
end

def toplevel_good_mexec
  self.module_exec do
    def inner
      puts "toplevel_good_mexec/inner"
    end
  end
  inner
end

puts "---"

toplevel_bad
inner rescue nil
toplevel_good_lambda
inner rescue nil
toplevel_good_eigen
inner rescue nil
toplevel_good_mexec
inner rescue nil
toplevel_good_ceval
inner rescue nil