Hi, I'm having a problem with "free" commas in macro expansions. I want to generate some function declarations (and implementations) from a user-supplied BOOST_PP_SEQ. The function declarations use enable_if to switch between two sets of interfaces based on the type that shall be returned. Nevermind the details, I've just used a trivial enabling condition here, the error is the same as when using mpl::contains<sometype, Type> in the real code. I've stripped the problem down and attached a test file, complete with my documented attempts to delay expansion of the comma somehow. The preprocessor succeeds when the enable_if or it's two template args are put into (parentheses), but this is no longer valid C++, of course. I guess I'm missing something, but I'm at the end of my Latin, as we say in Germany. Thanks, Marc -- Marc Mutz -- marc@klaralvdalens-datakonsult.se, mutz@kde.org Klarälvdalens Datakonsult AB, Platform-independent software solutions