Hi, I have a very simple header to simplify use of std::rel_ops with user defined classes, and I thought it might be interesting for inclusion in boost. It seems to work perfectly on gcc 4.0.2 20050901 (prerelease) (SUSE Linux), and I believe it's standard conforming. I haven't checked it with any other compiler, though. The usage is simple: You just write (with my current header, which of course would have to be adapted for boost): ---------------------------------------------------------------------- #include "relops.h" class MyClass: rel::ops // doesn't matter if you use public or private inheritance { // ... }; bool operator<(MyClass const&, MyClass const&) { /* ... */ } bool operator==(MyClass const&, MyClass const&) { /* ... */ } // now you can use all comparison operators: int main() { MyClass a, b; bool b = (a > b) // uses std::rel_ops::operator> } ---------------------------------------------------------------------- operator< and operator== of course can be defined anywhere the std::rel_ops operators will find them (e.g. they could be defined as class members instead). The header is obviously too simple to warrant its own boost library, but I could imagine it to be included e.g. in Boost.Utility. Alternatively it could be extended to support other typical operator implementations not covered by the standard, e.g. defining operator@ in terms of operator@=. Here's the actual code of the header: ---------------------------------------------------------------------- #ifndef RELOPS_H_INC #define RELOPS_H_INC #include <utility> namespace rel { using std::rel_ops::operator!=; using std::rel_ops::operator>; using std::rel_ops::operator>=; using std::rel_ops::operator<=; class ops {}; } #endif ---------------------------------------------------------------------- The trick is that by deriving from class rel::ops, you get the namespace rel looked into during Koenig lookup for function calls, esp. operators, involving your class type. Now, in namespace rel, the operators from std::rel_ops are found due to the explicit using declarations (obviously it would have been easier just to add class ops into std::rel_ops, but that's unfortunately prohibited by the standard). Deriving from class ops doesn't bring anything into your class than the additional Koenig lookup target, and with empty base class optimization it shouldn't affect your class otherwise as well. So what do you think?