The operator << must be defined in the boost namespace. See the error message of VC:see reference to function template instantiation 'std::basic_ostream<_Elem,_Traits> &boost::operator <<,int,std::string,boost::detail::variant::void_,boost::detail::variant::void_,boost::detail::variant::void_,boost::detail::variant::void_,boost::detail::variant::void_,boost::detail::variant::void_,boost::detail::variant::void_,boost::detail::variant::void_,boost::detail::variant::void_,boost::detail::variant::void_,boost::detail::variant::void_,boost::detail::variant::void_,boost::detail::variant::void_,boost::detail::variant::void_,boost::detail::variant::void_,boost::detail::variant::void_,boost::detail::variant::void_>(std::basic_ostream<_Elem,_Traits> &,const boost::variant &)' being compiled VC looks for boost::operator<< function and not ::operator<< function. But this should be documented in OutputStreamable. This would compile: #include<iostream> #include<vector> #include<string> #include namespace boost { template <typename T> std::ostream& operator<<(std::ostream& os, const std::vector<T>& v) { for(typename std::vector<T>::size_type i = 0; i < v.size(); ++i) os << v[i] << std::endl; return os; } } struct TpTemplateVariant { typedef boost::variant BoostVariant; }; typedef TpTemplateVariant::BoostVariant Tpvariant; int main () { Tpvariant p(5); std::cout << p; return 0; } Good Luck, Ovanes Markarian On Mon, June 26, 2006 12:45, CLAIRE, Narinder, Group Risk Mgmt wrote:

I apologise for emailing you directly .. but i canno access the mailing list from work.. However in response to your response.

The following doesn't compile either .. I get the error

error C2679: binary '<<' : no operator found which takes a right-hand operand of type 'const T0' (or there is no acceptable conversion)

On VC8

#include<iostream> #include<vector> #include<string>

#include

std::basic_ostream<char> &operator<<(std::basic_ostream<char> &theostream,const std::vector<unsigned long> &theVector) { for(unsigned long i(0);i

struct TpTemplateVariant { typedef boost::variant< std::vector<unsigned long>,

int,

std::string

...

BoostVariant; };

typedef TpTemplateVariant::BoostVariant Tpvariant;

int main () {

Tpvariant p(5); std::cout << p;

return 0;

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