I have searched the list archive and have not found anything on this subject. I have what looks like to be an issue with MSVC7.1 and unnamed namespaces (the _1 _2 and _3 are in unnamed namespaces in boost::lambda) See below: #include <boost/bind.hpp> #include <boost/Lambda/lambda.hpp> // adding my code to the boost::lambda namespace // below works fine namespace boost { namespace lambda { void MyFunction() { using namespace std; list<int> v; v.push_back(1); v.push_back(2); v.push_back(3); v.push_back(4); v.push_back(5); // Line below works for_each(v.begin(), v.end(), std::cout << _1 << ' '); } } } // Now global namespace void MyFunction() { using namespace std; using namespace boost; using namespace boost::lambda; list<int> v; v.push_back(1); v.push_back(2); v.push_back(3); v.push_back(4); v.push_back(5); // Line below fails with a "error C2872: '_1' : ambiguous symbol" for_each(v.begin(), v.end(), std::cout << _1 << ' '); // This line DOES work for_each(v.begin(), v.end(), std::cout << boost::lambda::_1 << ' '); } Has anyone else run into this? Also- I do not have the current CVS tree handy (I am using 1.31), is this a problem on 1.32? If it is workedaround in some fashion, I can just qualify every _1 and _2 until 1.32 comes out. Thanks for any help or suggestions Brian Braatz