Hello, I am refactoring our application which uses boost extensively in order to replace some boost-provided entities with their std counterparts defined in the C++11 standard. I've experienced a problem related to boost::bind placeholders defined in placeholders.hpp. The file begins with: namespace { static inline boost::arg<1> _1() { return boost::arg<1>(); } [...] unconditionally injecting the _N() functions into the global namespace scope. When I type "using namespace std::placeholders;" in order to use e.g. std::placeholders::_1, an unsolvable ambiguity occurs, as there is no way to transfer the boost-defined variants into an uncolliding namespace. Could you please add a macro in 1.49 which would allow me to override the default behaviour and define the functions in boost:: or boost::placeholders namespaces? #if defined(BOOST_USE_BOOST_PLACEHOLDERS_NAMESPACE) namespace boost { #else namespace { [...] Best regards, Piotr