Can you just please tell me what BOOST_READONLY_PROPERTY ( bool, (epv) ) will become once it is preprocessed ?

Something like this: class readonly_property123 : public boost::unit_test::readonly_property<bool> { typedef boost::unit_test::readonly_property<bool> base; friend class epv; // <-- here BOOST_PP is used typedef base::write_param_t write_param_t; public: readonly_property123() {} explicit readonly_property123( write_param_t init_v ) : base( init_v ) {} }

...

P.S. Paul should know the answer I don't think Paul knows about _all_ libraries that _use_ the PP library.

This has something to do with specific compiler bug in regards of PP.