To answer my own question - in case anyone else gets bitten by this - the answer is you need to provide overloads with both const and non-const reference RHS arguments to effectively hide the proto operator versions.
Still some hair left yours.... John.
Why answer you own question when I answered it for you yesterday?
Strange... that was exactly the answer I needed but it didn't show up in my inbox... would have saved me some time too :-(
And I think you have a reason to actual disable proto's operators instead of just hide them. Check the msg I sent yesterday.
The thing is I need left and right shift to be protoized, but I also need to be able to overload for stream out, I ended up with several overloads looking like: template <class Stream, class Backend> typename enable_if<is_convertible<Stream*, std::ostream*>, std::ostream&>::type operator << (Stream& os, big_number<Backend>& r) Which did the trick, and preserve protos shift operators, while still working with all stream types. BTW I do specify a proto grammar, and only enable the operators I need on a case by case basis, in this case though I would need to restrict the grammar so that proto's shift operators are only enabled for RHS arguments of integer type. Is that possible? John.