[Boost-commit] svn:boost r45896 - sandbox/units/boost/units

From: steven_at_[hidden]
Date: 2008-05-28 23:54:30

Author: steven_watanabe
Date: 2008-05-28 23:54:30 EDT (Wed, 28 May 2008)
New Revision: 45896
URL: http://svn.boost.org/trac/boost/changeset/45896

Log:
Added comment to io.hpp
Text files modified: 
   sandbox/units/boost/units/io.hpp |    25 ++++++++++++++++++++++++-               
   1 files changed, 24 insertions(+), 1 deletions(-)

Modified: sandbox/units/boost/units/io.hpp
==============================================================================
--- sandbox/units/boost/units/io.hpp	(original)
+++ sandbox/units/boost/units/io.hpp	2008-05-28 23:54:30 EDT (Wed, 28 May 2008)
@@ -338,6 +338,9 @@
 
 namespace io_impl {
 
+// These two overloads of symbol_string and name_string will
+// will pick up homogeneous_systems.  They simply call the
+// appropriate function with a heterogeneous_system.
 template<class Dimension,class System>
 inline std::string
 symbol_string(const unit<Dimension,System>&)
@@ -353,6 +356,7 @@
 }
 
 /// INTERNAL ONLY
+// this overload picks up heterogeneous units that are not scaled.
 template<class Dimension,class Units>
 inline std::string
 symbol_string(const unit<Dimension, heterogeneous_system<heterogeneous_system_impl<Units, Dimension, dimensionless_type> > >&)
@@ -365,6 +369,8 @@
     return(str);
 }
 
+// This overload is a special case for heterogeneous_system which
+// is really unitless
 /// INTERNAL ONLY
 inline std::string
 symbol_string(const unit<dimensionless_type, heterogeneous_system<heterogeneous_system_impl<dimensionless_type, dimensionless_type, dimensionless_type> > >&)
@@ -372,6 +378,8 @@
     return("dimensionless");
 }
 
+// this overload deals with heterogeneous_systems which are unitless
+// but scaled.
 /// INTERNAL ONLY
 template<class Scale>
 inline std::string
@@ -385,6 +393,7 @@
     return(str);
 }
 
+// this overload deals with scaled units.
 /// INTERNAL ONLY
 template<class Dimension,class Units,class Scale>
 inline std::string
@@ -411,6 +420,9 @@
     return(str);
 }
 
+// this overload catches scaled units that have a single base unit
+// raised to the first power.  It causes si::nano * si::meters to not
+// put parentheses around the meters.  i.e. nm rather than n(m)
 /// INTERNAL ONLY
 template<class Dimension,class Unit,class Scale>
 inline std::string
@@ -426,6 +438,10 @@
     return(str);
 }
 
+// this overload is necessary to disambiguate.
+// it catches units that are unscaled and have a single
+// base unit raised to the first power.  It is treated the
+// same as any other unscaled unit.
 /// INTERNAL ONLY
 template<class Dimension,class Unit>
 inline std::string
@@ -439,6 +455,12 @@
     return(str);
 }
 
+
+// this overload catches scaled units that have a single scaled base unit
+// raised to the first power.  It moves that scaling on the base unit
+// to the unit level scaling and recurses.  By doing this we make sure that
+// si::milli * si::kilograms will print g rather than mkg
+//
 /// INTERNAL ONLY
 template<class Dimension,class Unit,class UnitScale, class Scale>
 inline std::string
@@ -457,8 +479,9 @@
         >()));
 }
 
+// this overload disambuguates between the overload for an unscaled unit
+// and the overload for a scaled base unit raised to the first power.
 /// INTERNAL ONLY
-// disambiguate
 template<class Dimension,class Unit,class UnitScale>
 inline std::string
 symbol_string(const unit<Dimension, heterogeneous_system<heterogeneous_system_impl<list<heterogeneous_system_dim<scaled_base_unit<Unit, UnitScale>, static_rational<1> >, dimensionless_type>, Dimension, dimensionless_type> > >&)