class MessagePack::Packer

def register_type(type, klass, method_name = nil, &block)
  raise ArgumentError, "expected Module/Class got: #{klass.inspect}" unless klass.is_a?(Module)
  register_type_internal(type, klass, block || method_name.to_proc)
end

def registered_types
  list = []
  registered_types_internal.each_pair do |klass, ary|
    list << {type: ary[0], class: klass, packer: ary[1]}
  end
  list.sort{|a, b| a[:type] <=> b[:type] }
end

def type_registered?(klass_or_type)
  case klass_or_type
  when Class
    klass = klass_or_type
    registered_types.any?{|entry| klass <= entry[:class] }
  when Integer
    type = klass_or_type
    registered_types.any?{|entry| type == entry[:type] }
  else
    raise ArgumentError, "class or type id"
  end
end