ceph/src/boost/libs/parameter/test/literate/lazy-default-computation0.cpp

   1
   2 #include <boost/parameter.hpp>
   3 #include <string>
   4
   5 BOOST_PARAMETER_NAME(s1)
   6 BOOST_PARAMETER_NAME(s2)
   7 BOOST_PARAMETER_NAME(s3)
   8
   9 template <typename ArgumentPack>
  10 std::string f(ArgumentPack const& args)
  11 {
  12     std::string const& s1 = args[_s1];
  13     std::string const& s2 = args[_s2];
  14     typename boost::parameter::binding<
  15         ArgumentPack,tag::s3,std::string
  16     >::type s3 = args[_s3|(s1+s2)]; // always constructs s1+s2
  17     return s3;
  18 }
  19
  20 #include <boost/core/lightweight_test.hpp>
  21
  22 int main()
  23 {
  24     std::string x = f((_s1="hello,", _s2=" world", _s3="hi world"));
  25     BOOST_TEST_EQ(x, std::string("hi world"));
  26     return boost::report_errors();
  27 }
  28