On May 25, 2006, at 6:13 PM, Antonio Piccolboni wrote:
I just wanted to transform a vector of integers into a vecotr of strings, doesn't seem to be asking much
transform(ilabels.begin(), ilabels.end(), labels.begin(), lexical_cast<string>(_1));
gcc 4.0.2 doesn't like it at all
/usr/include/boost/lexical_cast.hpp:144: error: 'const class boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost ::lambda::bitwise_action<boost::lambda::leftshift_action>, boost::tuples::tuple<std::basic_stringstream<char, std::char_traits<char>, std::allocator<char> >&, boost::lambda::lambda_functor<boost::lambda::placeholder<1> >, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type> > >' has no member named 'fail'
<begin polemic, use flame retardant> Is it only me or does lambda lack orthogonality with anything else? Whenever I use lambda for anything non isomorphic to the the plain vanilla examples, the compiler goes ballistic <end polemic>
To make the above work, there would have to be an overload of lexical_cast function that understands what _1 is. Lambda and lexical_cast are separate libraries, which were developed in isolation of each other, and neither library has included such an overload. In the general case, it is not a realistic expectation that every function would be overloaded to accept placeholders. bind helps in many cases. Try: boost::lambda::bind(&boost::lexical_cast<std::string, int>, _1) (assuming that the value type of labels is int) Best, Jaakko