I am a little confused by the result_of tests, which means either I don't understand the library, or there is a problem as most compilers are passing! The basic case: struct int_result_type { typedef int result_type; }; BOOST_STATIC_ASSERT (( is_same< result_of< int_result_type(float) >::type, int >::value )); If I understand correctly, this is asking what is the result_of a function taking a float and returning an int_result_type. Intuitively, and from my reading of the tr1 docs, that should be an int_result_type, not an int as asserted in the test. My reading of tr1 says that result_of< int_result_type > should return an int, but NOT functions that return an int_result_type. This support being in there to support unary_function, binary_function, and other function objects following that protocol. -- AlisdairM