DSLs in ruby

gistfile1.rb

class Something
  def self.protector(name, &block)
    begin
      call_mod = self.const_get(:ExternalSystemCalls, false)
    rescue NameError
      call_mod = Module.new
      const_set(:ExternalSystemCalls, call_mod)
      include call_mod
    end
    begin
      protected_mod = self.const_get(:ProtectedCalls, false)
    rescue NameError
      protected_mod = Module.new
      const_set(:ProtectedCalls, protected_mod)
      include protected_mod
    end
    
    # Define the method that acutally does the call
    call_mod.send(:define_method, name, &block)
    
    # Define the method that wraps the call
    protected_mod.class_eval %{
      def #{name}(*args, &block)
        super
      rescue ExternalApiError => exception
        # do something with the exception
        return some value or raise your own error
      ensure
        # perform some cleanup
      end
    }
  end
  
  protector :signup do
    endpoint.call(:signup, true, "and other stuff", :whatever)
  end
  
  protector :disable do
    endpoint.call(:disable, false, "no idea what you'd do here", :nope)
  end
  
  
  # do this if you want to debug
  def disable(*)
    binding.pry
    super
  end
  # then delete this method after debugging.
end