Thanks for the link it was helpful.  I tried both methods and they both compiled.  It seems we can use the simpler form of decltype because it provides perfect forwarding.  Is this a correct interpretation?<div><br></div><div>
Neither of these two typedef seems to behave as I expected.  When creating a quantity with these typedefs I had to call them as a method to get the code to compile.</div><div><br></div><div>quantity&lt;si::velocity&gt; a(2.3 * nautical_miles_per_hour1());</div>
<div><div>quantity&lt;si::velocity&gt; b(2.4 * nautical_miles_per_hour2());</div><div>quantity&lt;si::velocity&gt; c(2.5 * si::meters_per_second);</div><div><br></div><div>Is there a way to get my type of nautical_miles_per_hour to behave like meters_per_second?</div>
<br class="Apple-interchange-newline"></div><div>Ryan</div><div><br></div><div>//Provided for the Discussion</div><div>using namespace boost::units;</div><div>typedef metric::nautical_mile_base_unit::unit_type  nautical_mile_unit;</div>
<div>typedef metric::hour_base_unit::unit_type  hour_unit;</div><div><br></div><div>typedef decltype(nautical_mile_unit() / hour_unit())  nautical_miles_per_hour1;</div><div>typedef divide_typeof_helper&lt;nautical_mile_unit, hour_unit&gt;::type  nautical_miles_per_hour2;</div>