A Ruby example of prepending a proxy module to a class to intercept method calls.

module_prepend.rb

module MethodBroadcaster
  def broadcast_calls_to(*method_names)
    proxy = Module.new
    method_names.each do |method_name|
      proxy.define_method(method_name) do |*args, **kwargs, &block|
        arg_strings = args.map(&:inspect)
        kwarg_strings = kwargs.map{|k, v| "#{k}: #{v.inspect}" }
        all_arg_strings = arg_strings + kwarg_strings
        puts "#{method_name}(#{all_arg_strings.join(', ')})"
        super(*args, **kwargs, &block)
      end
    end
    self.prepend proxy
  end
end

class Foo
  extend MethodBroadcaster
  def positional_arguments(arg1, arg2)
    p [arg1, arg2]
  end
  def keyword_arguments(foo:, bar: "bar!")
    p [foo, bar]
  end
  def positional_and_keyword_arguments(arg1, arg2, foo:, bar: "bar!")
    p [arg1, arg2, foo, bar]
    puts yield("block arg") if block_given?
  end
  broadcast_calls_to :positional_arguments, :keyword_arguments, :positional_and_keyword_arguments
end

foo = Foo.new
foo.positional_arguments("arg1!", "arg2!")
# => positional_arguments("arg1!", "arg2!")
# => ["arg1!", "arg2!"]

foo.keyword_arguments(foo: "foo!")
# => keyword_arguments(foo: "foo!")
# => ["foo!", "bar!"]

foo.positional_and_keyword_arguments("arg1!", "arg2!", foo: "foo!", bar: "bar!!")
# => positional_and_keyword_arguments("arg1!", "arg2!", foo: "foo!", bar: "bar!!")
# => ["arg1!", "arg2!", "foo!", "bar!!"]

foo.positional_and_keyword_arguments("arg1!", "arg2!", foo: "foo!") { |block_arg| "block got #{block_arg}!" }
# => positional_and_keyword_arguments("arg1!", "arg2!", foo: "foo!")
# => ["arg1!", "arg2!", "foo!", "bar!"]
# => block got block arg!