void
Init_Object()
{
    VALUE metaclass;

    rb_cObject = boot_defclass("Object", 0);
    rb_cModule = boot_defclass("Module", rb_cObject);
    rb_cClass =  boot_defclass("Class",  rb_cModule);

    metaclass = RBASIC(rb_cObject)->klass = rb_singleton_class_new(rb_cClass);
    rb_singleton_class_attached(metaclass, rb_cObject);
    metaclass = RBASIC(rb_cModule)->klass = rb_singleton_class_new(metaclass);
    rb_singleton_class_attached(metaclass, rb_cModule);
    metaclass = RBASIC(rb_cClass)->klass = rb_singleton_class_new(metaclass);
    rb_singleton_class_attached(metaclass, rb_cClass);
    ...