[Boost-commit] svn:boost r66188 - sandbox/variadic_templates/sandbox

Subject: [Boost-commit] svn:boost r66188 - sandbox/variadic_templates/sandbox
From: cppljevans_at_[hidden]
Date: 2010-10-25 14:56:45

Author: cppljevans
Date: 2010-10-25 14:56:42 EDT (Mon, 25 Oct 2010)
New Revision: 66188
URL: http://svn.boost.org/trac/boost/changeset/66188

Log:
Use functor instead of function pointer:

/home/evansl/download/gcc/4.5.1-release/install/bin/g++ -Wl,-rpath /home/evansl/download/gcc/4.5.1-release/install/lib64  /home/evansl/prog_dev/boost-svn/ro/trunk/sandbox-local/build/gcc4_5_1v/boost-svn/ro/sandbox/rw/variadic_templates/sandbox/varbin.o -o /home/evansl/prog_dev/boost-svn/ro/trunk/sandbox-local/build/gcc4_5_1v/boost-svn/ro/sandbox/rw/variadic_templates/sandbox/varbin.exe
/home/evansl/prog_dev/boost-svn/ro/trunk/sandbox-local/build/gcc4_5_1v/boost-svn/ro/sandbox/rw/variadic_templates/sandbox/varbin.exe 
1
6
60

Compilation finished at Mon Oct 25 13:55:29

Text files modified: 
   sandbox/variadic_templates/sandbox/varbin.cpp |    40 ++++++++++++++++++++++++++++++----------
   1 files changed, 30 insertions(+), 10 deletions(-)

Modified: sandbox/variadic_templates/sandbox/varbin.cpp
==============================================================================
--- sandbox/variadic_templates/sandbox/varbin.cpp	(original)
+++ sandbox/variadic_templates/sandbox/varbin.cpp	2010-10-25 14:56:42 EDT (Mon, 25 Oct 2010)
@@ -2,21 +2,41 @@
 //  see if variadic reduce is possible using variadic templates.
 //
 //Result:
-// //  No, apparently b... is not an arg pack.
-// //
-// int add(int a,int b){return a+b;}
+//  Yes.
+//
+
+struct add
+{
+      template<typename T>
+      T
+    operator()(T a,T b)
+    { 
+        return a+b;
+    }
 
-template<typename T, typename... U>
-T fold(T (*op)(T,T), T z, U... a)
+};
+
+template<typename Op, typename T, typename... U>
+T fold(Op op, T z, U... a)
 ;
 
-template<typename T>
-T fold(T (*op)(T,T), T z, T a)
-{ return op(z,a)
+template<typename Op, typename T>
+T fold(Op op, T z)
+{ return z
 ;}
 
-template<typename T, typename... U>
-T fold(T (*op)(T,T), T z, T a, U... b)
+template<typename Op, typename T, typename... U>
+T fold(Op op, T z, T a, U... b)
 { return op(z,fold(op,a,b...))
 ;}
 
+#include <iostream>
+
+int main(void)
+{
+    add op;
+    std::cout<<fold(op,1)<<"\n";
+    std::cout<<fold(op,1,2,3)<<"\n";
+    std::cout<<fold(op,10,20,30)<<"\n";
+    return 0;
+}