Hello, I did this (code shortened to what is interesting): class imathprint : public print_dflt { GINAC_DECLARE_PRINT_CONTEXT(imathprint, print_dflt) public: optstack* poptions; // imathprint-specific print options imathprint(std::ostream & os, optstack* popt, unsigned opt = 0) : print_dflt(os, opt), poptions(popt) {}; static void init(); }; DECLARE_FUNCTION_3P(partialdiff) static void partialdiff_print_imath(..., const imathprint &c) {} static void partialdiff_print_ltx(..., const print_context &c) {} REGISTER_FUNCTION(partialdiff, ... print_func<print_latex>(&partialdiff_print_ltx). print_func<imathprint>(&partialdiff_print_imath). ...); This gives me an error func.cpp:1310: error: no matching function for call to ‘GiNaC::function_options::print_func(void (*)(const GiNaC::ex&, const GiNaC::ex&, const GiNaC::ex&, const imathprint&)) But doing the same kind of thing in GINAC_IMPLEMENT_REGISTERED_CLASS_OPT works! What I am trying to do is to create an extended print context imathprint which has more options and also options of non-integer type. Any better ideas? Thank you, Jan