class MessagePack::Unpacker

def register_type(type, klass = nil, method_name = nil, &block)
  if klass && method_name
    block = klass.method(method_name).to_proc
  elsif !block_given?
    raise ArgumentError, "register_type takes either 3 arguments or a block"
  end
  register_type_internal(type, klass, block)
end

def registered_types
  list = []
  registered_types_internal.each_pair do |type, ary|
    list << {type: type, class: ary[0], unpacker: 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