remove_const

/*
 *  call-seq:
 *     remove_const(sym)   => obj
 *  
 *  Removes the definition of the given constant, returning that
 *  constant's value. Predefined classes and singleton objects (such as
 *  <i>true</i>) cannot be removed.
 */

VALUE
rb_mod_remove_const(mod, name)
    VALUE mod, name;
{
    ID id = rb_to_id(name);
    VALUE val;

    if (!rb_is_const_id(id)) {
	rb_name_error(id, "`%s' is not allowed as a constant name", rb_id2name(id));
    }
    if (!OBJ_TAINTED(mod) && rb_safe_level() >= 4)
	rb_raise(rb_eSecurityError, "Insecure: can't remove constant");
    if (OBJ_FROZEN(mod)) rb_error_frozen("class/module");

    if (RCLASS(mod)->iv_tbl && st_delete(ROBJECT(mod)->iv_tbl, (st_data_t*)&id, &val)) {
	if (val == Qundef) {
	    autoload_delete(mod, id);
	    val = Qnil;
	}
	return val;
    }
    if (rb_const_defined_at(mod, id)) {
	rb_name_error(id, "cannot remove %s::%s",
		 rb_class2name(mod), rb_id2name(id));
    }
    rb_name_error(id, "constant %s::%s not defined",
		  rb_class2name(mod), rb_id2name(id));
    return Qnil;		/* not reached */
}