to) the
    Signals2 library. While these interfaces are generally enable more
    straighforward implementation of the signals &amp; slots
    libraries, the combiners are unfortunately not reusable (either in
    other signals &amp; slots libraries or within other generic
    algorithms), and the learning curve is steepened slightly to learn
    the specific combiner interface.</p>
<p> The Signals2 formulation of combiners is based on the
    combiner using the "pull" mode of communication, instead of the