The Ruby 2 prepend() method makes method chaining a lot easier.

gistfile1.rb

module SystemHook
  private
  def system(*args)
    super.tap do |result|
      puts "system(#{args.join(', ')}) returned #{result.inspect}"
    end
  end
end

class Object
  prepend SystemHook
end

system("date")
system("kangaroo", "-hop 10", "skippy")

How are you calling a private method? Is is because we are inside main, which is an instance of Object?

@roguevalley In Ruby, a private method is defined as a method which can't be called with the explicit receiver but only with omitted self.
So system(...) can call even a private method.

Is there are any ability to access an old system method?