id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
7138	Output of a UDT with autoprefix  requires specialization of auto_prefix_norm	Paul A. Bristow	Steven Watanabe	"Output of a UDT with autoprefix  requires specialization of auto_prefix_norm for the scaling to take place.  For example, to get expected scaling to kilometers from

quantity<length, measurement<double> > 
biglen(measurement<double>(12345.0,123.0)*meters); autoscaled = 12.345(+/-0.123) km

This can be achieved by adding this to measurement.hpp (where Y is the type of UDT)


{{{
// Specialization of autoprefix_norm for UDTboost::units::measurement<Y>
// See io.hpp.
// This specialization is required to get autoprefix to work with this class.

template<class Y>
typename autoprefix_norm_impl<boost::units::measurement<Y>, true>::type
autoprefix_norm(const boost::units::measurement<Y> & arg)
{
  return autoprefix_norm_impl<Y, true>::call(arg);
}
}}}
However this assumes that the class Y is convertible to double.
autoprefix_norm_impl<T, true>::type appears to be always double.
I am unclear if this is checked or is the responsibility or the user?
"	Bugs	new	Boost 1.51.0	units	Boost 1.51.0	Problem		units autoprefix UDT