simpler.rb

def test(name)
  module_eval("private; def #{name}; end")
end

def test2(name, private: nil)
  module_eval("private; def #{name}; end")
end

module Foo
  puts '-'* 40
  test("foo")
  puts '-'* 40
  test2("bar", private: nil)
  puts '-'* 40
end

void-context.rb

$VERBOSE = true

def delegate(*methods, to: nil, private: nil)
  location = caller_locations(1, 1).first
  file, line = location.path, location.lineno

  receiver = to.to_s

  method_def = []
  method_names = []

  method_def << "private" if private

  methods.each do |method|
    method_name = method
    method_names << method_name.to_sym

    method = method.to_s
    method_name = method_name.to_s

    method_def <<
      "def #{method_name}" <<
      "end"
  end
  source = method_def.join("\n")
  puts "------ eval -------"
  puts source
  puts "------ end-eval -------"
  module_eval(source, file, line)
  method_names
end

module Foo
  puts "this warns:"
  delegate(:street, to: :@place, private: true)
end

module Bar
  puts "this doesn't:"
  module_eval <<~RUBY, __FILE__, __LINE__ + 1
    private
    def street
    end
  RUBY
end