variable.c:1676
void
rb_define_class_variable(klass, name, val)
    VALUE klass;
    const char *name;
    VALUE val;
{
    ID id = rb_intern(name);

    if (!rb_is_class_id(id)) {
	rb_name_error(id, "wrong class variable name %s", name);
    }
    rb_cvar_set(klass, id, val, Qtrue);
}
