[Boost-commit] svn:boost r59374 - trunk/boost/accumulators/numeric/functional

Subject: [Boost-commit] svn:boost r59374 - trunk/boost/accumulators/numeric/functional
From: eric_at_[hidden]
Date: 2010-01-30 19:27:22

Author: eric_niebler
Date: 2010-01-30 19:27:21 EST (Sat, 30 Jan 2010)
New Revision: 59374
URL: http://svn.boost.org/trac/boost/changeset/59374

Log:
avoid premature template evaluation in operator overload return types
Text files modified: 
   trunk/boost/accumulators/numeric/functional/valarray.hpp |    21 +++++++++++++++------                   
   trunk/boost/accumulators/numeric/functional/vector.hpp   |    21 +++++++++++++++------                   
   2 files changed, 30 insertions(+), 12 deletions(-)

Modified: trunk/boost/accumulators/numeric/functional/valarray.hpp
==============================================================================
--- trunk/boost/accumulators/numeric/functional/valarray.hpp	(original)
+++ trunk/boost/accumulators/numeric/functional/valarray.hpp	2010-01-30 19:27:21 EST (Sat, 30 Jan 2010)
@@ -29,12 +29,21 @@
 {
     namespace operators
     {
+        namespace detail
+        {
+            template<typename Fun>
+            struct make_valarray
+            {
+                typedef std::valarray<typename Fun::result_type> type;
+            };
+        }
+
         ///////////////////////////////////////////////////////////////////////////////
         // Handle valarray<Left> / Right where Right is a scalar and Right != Left.
         template<typename Left, typename Right>
-        typename enable_if<
+        typename lazy_enable_if<
             mpl::and_<is_scalar<Right>, mpl::not_<is_same<Left, Right> > >
-          , std::valarray<typename functional::divides<Left, Right>::result_type>
+          , detail::make_valarray<functional::divides<Left, Right> >
         >::type
         operator /(std::valarray<Left> const &left, Right const &right)
         {
@@ -50,9 +59,9 @@
         ///////////////////////////////////////////////////////////////////////////////
         // Handle valarray<Left> * Right where Right is a scalar and Right != Left.
         template<typename Left, typename Right>
-        typename enable_if<
+        typename lazy_enable_if<
             mpl::and_<is_scalar<Right>, mpl::not_<is_same<Left, Right> > >
-          , std::valarray<typename functional::multiplies<Left, Right>::result_type>
+          , detail::make_valarray<functional::multiplies<Left, Right> >
         >::type
         operator *(std::valarray<Left> const &left, Right const &right)
         {
@@ -68,9 +77,9 @@
         ///////////////////////////////////////////////////////////////////////////////
         // Handle valarray<Left> + valarray<Right> where Right != Left.
         template<typename Left, typename Right>
-        typename disable_if<
+        typename lazy_disable_if<
             is_same<Left, Right>
-          , std::valarray<typename functional::plus<Left, Right>::result_type>
+          , detail::make_valarray<functional::plus<Left, Right> >
         >::type
         operator +(std::valarray<Left> const &left, std::valarray<Right> const &right)
         {

Modified: trunk/boost/accumulators/numeric/functional/vector.hpp
==============================================================================
--- trunk/boost/accumulators/numeric/functional/vector.hpp	(original)
+++ trunk/boost/accumulators/numeric/functional/vector.hpp	2010-01-30 19:27:21 EST (Sat, 30 Jan 2010)
@@ -28,12 +28,21 @@
 {
     namespace operators
     {
+        namespace detail
+        {
+            template<typename Fun>
+            struct make_vector
+            {
+                typedef std::vector<typename Fun::result_type> type;
+            };
+        }
+
         ///////////////////////////////////////////////////////////////////////////////
         // Handle vector<Left> / Right where Right is a scalar.
         template<typename Left, typename Right>
-        typename enable_if<
+        typename lazy_enable_if<
             is_scalar<Right>
-          , std::vector<typename functional::divides<Left, Right>::result_type>
+          , detail::make_vector<functional::divides<Left, Right> >
         >::type
         operator /(std::vector<Left> const &left, Right const &right)
         {
@@ -64,9 +73,9 @@
         ///////////////////////////////////////////////////////////////////////////////
         // Handle vector<Left> * Right where Right is a scalar.
         template<typename Left, typename Right>
-        typename enable_if<
+        typename lazy_enable_if<
             is_scalar<Right>
-          , std::vector<typename functional::multiplies<Left, Right>::result_type>
+          , detail::make_vector<functional::multiplies<Left, Right> >
         >::type
         operator *(std::vector<Left> const &left, Right const &right)
         {
@@ -82,9 +91,9 @@
         ///////////////////////////////////////////////////////////////////////////////
         // Handle Left * vector<Right> where Left is a scalar.
         template<typename Left, typename Right>
-        typename enable_if<
+        typename lazy_enable_if<
             is_scalar<Left>
-          , std::vector<typename functional::multiplies<Left, Right>::result_type>
+          , detail::make_vector<functional::multiplies<Left, Right> >
         >::type
         operator *(Left const &left, std::vector<Right> const &right)
         {