I would like to propose to your review the following addition to the type_traits library, available at the following addresses: https://svn.boost.org/trac/boost/browser/sandbox/type_traits http://dl.free.fr/lRm4VL6WP/type_traits.tar.bz2 The purpose of the addition is to add type traits to detect if unary and binary operators can be applied to given types. For example, is "x<y" or "!x" or "x+y" meaningful? If required, the return type of such an expression is checked to know if it is convertible to a given type. Default behaviour is to not check the return type. The following traits are added: // binary operators: template < typename LHS, typename RHS=LHS, typename RET=void > == has_operator_equal_to != has_operator_not_equal_to > has_operator_greater >= has_operator_greater_equal < has_operator_less <= has_operator_less_equal + has_operator_plus - has_operator_minus * has_operator_multiplies / has_operator_divides % has_operator_modulus && has_operator_logical_and || has_operator_logical_or & has_operator_bit_and | has_operator_bit_or ^ has_operator_bit_xor // unary operators: template < typename RHS, typename RET=void > + has_operator_unary_plus - has_operator_unary_minus ! has_operator_logical_not This new version reflects the discussions we had on the list: http://thread.gmane.org/gmane.comp.lib.boost.devel/194625 In particular about the check or not of the return type. All operators are now included and not only comparison binary operators. Example: has_operator_less<LHS, RHS, RET>::value_type is the type bool. has_operator_less<int> inherits from true_type. has_operator_less<int, int, std::string> inherits from false_type. has_operator_unary_minus<int, long> inherits from true_type. has_operator_unary_minus<double, int> inherits from true_type. has_operator_unary_minus<int, std::string> inherits from false_type. Documentation is accessible at libs/type_traits/doc/html/index.html in the archive. Regards, Frédéric PS: tested with g++ 4.4.5 on i686-linux.