I’m looking for a portable version of __if_exists (VS.NET keyword) and unfortunately google turned up nothing good. I use boost fairly regular and checked boost::type_traits but found nothing that seemed to similar. Has anyone heard of something that can accomplish this? As a side note, I got inspired by the technique used when to enable/disable template class specializations using boost::enable_if and succeeded in creating something that managed this: struct x { typedef std::string aggregated_type; }; struct y { }; int main(int, char*) { std::cout << is_aggregated_type_available<x>::value << std::endl; std::cout << is_aggregated_type_available<y>::value << std::endl; } Prints: 1 0 Which means that x has an aggregated type named aggregated_type. Unfortunately I failed miserably when trying to test for member variables and member functions. So I thought I take my chance and post my question here. Regards, Mårten Rånge PS. I want to give a big thank-you to the boost community for putting 1.32.0 together. It was worth waiting for. PS. I attached is_aggregated_type_available in case anyone is interested. Unfortunately only tested on VS.NET 2003 and VS.NET 2005 Beta 1 but it feels like it should work on more compilers due to the similarities with the examples in boost::enable_if documentation.