[Boost-bugs] [Boost C++ Libraries] #9582: Boost.Units: conversion to double with prefixed unit

Subject: [Boost-bugs] [Boost C++ Libraries] #9582: Boost.Units: conversion to double with prefixed unit
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2014-01-16 08:59:23

#9582: Boost.Units: conversion to double with prefixed unit
-------------------------------------+-----------------------------
 Reporter:  richel@…                 |      Owner:  matthiasschabel
     Type:  Feature Requests         |     Status:  new
Milestone:  To Be Determined         |  Component:  units
  Version:  Boost 1.54.0             |   Severity:  Cosmetic
 Keywords:  Units conversion prefix  |
-------------------------------------+-----------------------------
 A post to the Boost-users maillinglist suggested me to request this
 feature.

 In the code below, I convert a double that is known to be in millimeters
 to a unit and back again. The latter fails, where it works as expected for
 meters.

 I think that adding this feature increases the symmetry in the use of
 Boost.Units, as I have emphasised in my code.

 I am aware of the great care the Boost.Units developers have in
 maintaining type-safety, so it might be that I am unaware of code
 compiling that shouldn't would this request be acknowledged.

 {{{
 using boost::units::conversion_factor;
 using boost::units::quantity;
 using boost::units::si::length;
 using boost::units::si::meter;
 using boost::units::si::milli;
 typedef quantity<length> Length;

 //This value is read from file
 const double x_in_mm = 1.0;

 //Add units
 const Length x(x_in_mm * (milli * meter)); //Brackets added for emphasis

 const double x_again_in_m  = x / meter; //Works

 const double x_again_in_mm {
   x / (milli * meter) //Same brackets as at emphasis
 }; //Why doesn't this?

 assert(x_in_mm == x_again_in_mm);
 }}}

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/9582>
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