--- C:/Users/Paul/AppData/Local/Temp/measurement.hpp-revBASE.svn000.tmp.hpp	Sat Jan 15 08:11:51 2011
+++ I:/boost-trunk/libs/units/example/measurement.hpp	Fri Aug 17 15:10:44 2012
@@ -1,4 +1,4 @@
-// Boost.Units - A C++ library for zero-overhead dimensional analysis and 
+// Boost.Units - A C++ library for zero-overhead dimensional analysis and
 // unit/quantity manipulation and conversion
 //
 // Copyright (C) 2003-2008 Matthias Christian Schabel
@@ -19,6 +19,8 @@
 #include <boost/io/ios_state.hpp>
 #include <boost/units/static_rational.hpp>
 
+#include <boost/type_traits.hpp>
+
 namespace boost {
 
 namespace units {
@@ -35,89 +37,87 @@
 
 template<class Y>
 class measurement
-{    
+{
     public:
         typedef measurement<Y>                  this_type;
         typedef Y                               value_type;
-        
+
         measurement(const value_type& val = value_type(),
-                    const value_type& err = value_type()) : 
+                    const value_type& err = value_type()) :
             value_(val),
-            uncertainty_(std::abs(err)) 
+            uncertainty_(std::abs(err))
         { }
-        
-        measurement(const this_type& source) : 
+
+        measurement(const this_type& source) :
             value_(source.value_),
-            uncertainty_(source.uncertainty_) 
+            uncertainty_(source.uncertainty_)
         { }
-        
+
         //~measurement() { }
-        
+
         this_type& operator=(const this_type& source)
         {
             if (this == &source) return *this;
-            
+
             value_ = source.value_;
             uncertainty_ = source.uncertainty_;
-            
+
             return *this;
         }
-        
+
         operator value_type() const    { return value_; }
-        
+
         value_type value() const       { return value_; }
         value_type uncertainty() const { return uncertainty_; }
         value_type lower_bound() const { return value_-uncertainty_; }
         value_type upper_bound() const { return value_+uncertainty_; }
-        
-        this_type& operator+=(const value_type& val)            
-        { 
-            value_ += val; 
-            return *this; 
+
+        this_type& operator+=(const value_type& val)
+        {
+            value_ += val;
+            return *this;
         }
-        
-        this_type& operator-=(const value_type& val)            
-        { 
-            value_ -= val; 
-            return *this; 
+
+        this_type& operator-=(const value_type& val)
+        {
+            value_ -= val;
+            return *this;
         }
-        
-        this_type& operator*=(const value_type& val)            
-        { 
-            value_ *= val; 
-            uncertainty_ *= val; 
-            return *this; 
+
+        this_type& operator*=(const value_type& val)
+        {
+            value_ *= val;
+            uncertainty_ *= val;
+            return *this;
         }
-        
-        this_type& operator/=(const value_type& val)            
-        { 
-            value_ /= val; 
-            uncertainty_ /= val; 
-            return *this; 
+
+        this_type& operator/=(const value_type& val)
+        {
+            value_ /= val;
+            uncertainty_ /= val;
+            return *this;
         }
-        
+
         this_type& operator+=(const this_type& /*source*/);
-        this_type& operator-=(const this_type& /*source*/);        
-        this_type& operator*=(const this_type& /*source*/);        
+        this_type& operator-=(const this_type& /*source*/);
+        this_type& operator*=(const this_type& /*source*/);
         this_type& operator/=(const this_type& /*source*/);
 
+
+
     private:
         value_type          value_,
                             uncertainty_;
-};
+}; // class measurement
 
-}
+} // namespace units
+}  // namespace boost
 
-}
-
 #if BOOST_UNITS_HAS_BOOST_TYPEOF
-
-BOOST_TYPEOF_REGISTER_TEMPLATE(boost::units::measurement, 1)
-
+  BOOST_TYPEOF_REGISTER_TEMPLATE(boost::units::measurement, 1)
 #endif
 
 namespace boost {
-
 namespace units {
 
 template<class Y>
@@ -127,7 +127,7 @@
 {
     uncertainty_ = std::sqrt(sqr(uncertainty_)+sqr(source.uncertainty_));
     value_ += source.value_;
-    
+
     return *this;
 }
 
@@ -138,7 +138,7 @@
 {
     uncertainty_ = std::sqrt(sqr(uncertainty_)+sqr(source.uncertainty_));
     value_ -= source.value_;
-    
+
     return *this;
 }
 
@@ -151,7 +151,7 @@
               std::sqrt(sqr(uncertainty_/value_)+
                         sqr(source.uncertainty_/source.value_));
     value_ *= source.value_;
-    
+
     return *this;
 }
 
@@ -164,7 +164,7 @@
               std::sqrt(sqr(uncertainty_/value_)+
                         sqr(source.uncertainty_/source.value_));
     value_ /= source.value_;
-    
+
     return *this;
 }
 
@@ -268,41 +268,41 @@
 }
 
 /// specialize power typeof helper
-template<class Y,long N,long D> 
+template<class Y,long N,long D>
 struct power_typeof_helper<measurement<Y>,static_rational<N,D> >
-{ 
+{
     typedef measurement<
         typename power_typeof_helper<Y,static_rational<N,D> >::type
-    > type; 
-    
-    static type value(const measurement<Y>& x)  
-    { 
+    > type;
+
+    static type value(const measurement<Y>& x)
+    {
         const static_rational<N,D>  rat;
 
         const Y m = Y(rat.numerator())/Y(rat.denominator()),
                 newval = std::pow(x.value(),m),
                 err = newval*std::sqrt(std::pow(m*x.uncertainty()/x.value(),2));
-        
+
         return type(newval,err);
     }
 };
 
 /// specialize root typeof helper
-template<class Y,long N,long D> 
-struct root_typeof_helper<measurement<Y>,static_rational<N,D> >                
-{ 
+template<class Y,long N,long D>
+struct root_typeof_helper<measurement<Y>,static_rational<N,D> >
+{
     typedef measurement<
         typename root_typeof_helper<Y,static_rational<N,D> >::type
-    > type; 
-    
-    static type value(const measurement<Y>& x)  
-    { 
+    > type;
+
+    static type value(const measurement<Y>& x)
+    {
         const static_rational<N,D>  rat;
 
         const Y m = Y(rat.denominator())/Y(rat.numerator()),
                 newval = std::pow(x.value(),m),
                 err = newval*std::sqrt(std::pow(m*x.uncertainty()/x.value(),2));
-        
+
         return type(newval,err);
     }
 };
@@ -310,18 +310,85 @@
 // stream output
 template<class Y>
 inline
-std::ostream& operator<<(std::ostream& os,const measurement<Y>& val)
+std::ostream& operator<<(std::ostream& os, const measurement<Y>& val)
 {
     boost::io::ios_precision_saver precision_saver(os);
     boost::io::ios_flags_saver flags_saver(os);
-    
-    os << val.value() << "(+/-" << val.uncertainty() << ")";
-    
+    std::streamsize w = os.width();
+    if (w > 0)
+    { // Need to output both as one string to avoid disrupting column width.
+      std::ostringstream oss;
+      oss << val.value() << "(+/-" << val.uncertainty() << ")";
+      os.width(w);
+      os << oss.str();
+    }
+    else
+    { // Output direct to os.
+       os << val.value() << "(+/-" << val.uncertainty() << ")";
+    }
     return os;
 }
 
+// Specialization of autoprefix_norm for UDT boost::units::measurement<Y>
+// See io.hpp.
+
+// Note that autoprefix_norm_impl is in the boost::units namespace,
+// but autoprefix_norm being specialized is in the UDT namespace (here measd).
+// If the UDT is parameterized for floating-point type (FPT), as the
+// example measurement, then its type can be used as a template parameter
+// to autoprefix_norm_impl, but if not then double or other FPT is needed.
+// This type *must* be convertible to double.
+// If this may involve loss of precision then a warning will be issued.
+/*
+
+using  boost::units::measd;
+using boost::units::autoprefix_norm_impl;
+
+autoprefix_norm_impl<measd, true>::type
+autoprefix_norm(const measd & arg)
+{
+  return autoprefix_norm_impl<double, true>::call(arg);
+}
+// Specialization of autoprefix_norm for UDT boost::units::measurement<float>
+// Warns "conversion from 'long double' to 'double', possible loss of data"
+autoprefix_norm_impl<boost::units::measurement<float>, true>::type
+autoprefix_norm(const boost::units::measurement<float> & arg)
+{
+  return autoprefix_norm_impl<double, true>::call(arg); // double or float (long double warns of loss)
+}
+
+// Specialization of autoprefix_norm for UDT boost::units::measurement<double>
+// Warns "conversion from 'long double' to 'double', possible loss of data"
+autoprefix_norm_impl<double, true>::type
+autoprefix_norm(const boost::units::measurement<double> & arg)
+{
+  return autoprefix_norm_impl<double, true>::call(arg); // double or float (long double warns of loss)
+}
+
+// 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<double, true>::call(arg);
+//}
+*/
+
+using boost::units::autoprefix_norm_impl;
+using boost::units::measurement; // Might be in another namespace?
+
+template<class Y>
+typename autoprefix_norm_impl<measurement<Y>, true>::type
+autoprefix_norm(const measurement<Y> & arg)
+{
+  // If measurement was not parameterized on floating-point type, might use
+  // `return autoprefix_norm_impl<double, true>::call(arg);`
+  // but must be conertible to `double`.
+  return autoprefix_norm_impl<Y, true>::call(arg);
+}
+
+
 } // namespace units
-
 } // namespace boost
 
 #endif // BOOST_UNITS_MEASUREMENT_HPP