Maurizio Vitale wrote:
Hi,
I'm trying to get boost::proto to turn udt(v1,v2) into a parse tree. Up to now I haven't got past the compiler asking for an udt::operator()(int,int).
I can probably define such an operator for my UDT and return a proto::expr tree, but I was hoping in proto providing overloads so that I don't have to do it for all my types.
I've looked into expr.hpp and there seem to be something related to this, but I don't seem to be able to make use of it.
What is the best way to achieve what I'm trying?
As you noticed, proto::expr<> has operator() overloads, and everything in proto is an expr<>, including terminals, so you can do this: struct udt_tag {}; proto::terminal<udt_tag>::type const udt = {{}}; And now udt(v1,v2) will build parse trees. If you want udt to have extra member functions, you would use proto::extends<>, like this: struct udt_ex : proto::extends<proto::terminal<udt_tag>::type, udt_ex> { udt_ex() {} using proto::extends<proto::terminal<udt_tag>::type, udt_ex> ::operator=; void do_stuff() {...} ... }; udt_ex const udt; HTH, -- Eric Niebler Boost Consulting www.boost-consulting.com