dup

/*
 *  call-seq:
 *     obj.dup -> an_object
 *  
 *  Produces a shallow copy of <i>obj</i>---the instance variables of
 *  <i>obj</i> are copied, but not the objects they reference.
 *  <code>dup</code> copies the tainted state of <i>obj</i>. See also
 *  the discussion under <code>Object#clone</code>. In general,
 *  <code>clone</code> and <code>dup</code> may have different semantics
 *  in descendent classes. While <code>clone</code> is used to duplicate
 *  an object, including its internal state, <code>dup</code> typically
 *  uses the class of the descendent object to create the new instance.
 *
 *  This method may have class-specific behavior.  If so, that
 *  behavior will be documented under the #+initialize_copy+ method of
 *  the class.
 */

VALUE
rb_obj_dup(obj)
    VALUE obj;
{
    VALUE dup;

    if (rb_special_const_p(obj)) {
        rb_raise(rb_eTypeError, "can't dup %s", rb_obj_classname(obj));
    }
    dup = rb_obj_alloc(rb_obj_class(obj));
    init_copy(dup, obj);

    return dup;
}