From: Yuval Ronen <ronen_yuval@yahoo.com>

Also notice the third operator(): if you wanted the opposite - convert the int to float and store the plus result in the variant, thus changing the type of the variant's content, then I don't know how to do it. I mean, you could make the visitor derived from static_visitor<float>, make the operators() return the result, and store it in the variant later, but that would also make int+int result a float, which might be not good for you...

I had the same problem with a visitor that I wanted to mutate the variant type. The solution I came up with was to wrap the variant in a class, then define my various methods in the class and forward them to the variant, then assign the result back to the class, like so: typedef [...whatever...] private_variant_type; class variant_type { private: private_variant_type _value; public: variant_type operator+= (const variant_type& lhs, const variant_type& rhs) { _value = boost::apply_visitor(addition_visitor(), lhs, rhs); return *this; } }; The addition_visitor class returns private_variant_type. I think this is a little clunky, but it DOES work. It would be great if there were a way to change the type of a variant from within a visitor! - James Jones Administrative Data Mgmt. Webmaster 375 Raritan Center Pkwy, Suite A Data Architect Edison, NJ 08837