You can only apply enable_if to template arguments of the function and not of the class which contains the function, but you can't declare a virtual function template... So this is your dilemma. Regards, Ovanes On Tue, Aug 18, 2009 at 7:23 PM, topoden <_dvt_@mail.ru> wrote:
Hello,
I'm trying to use boost::enable_if to customize function declaration for a particular set of template arguments. But instead of using SFINAE to remove incorrect declaration it produces error. See the example below to see better what I mean:
#include <boost/utility.hpp> #include <boost/type_traits.hpp>
template<class A, class B> struct BaseListener { typename boost::disable_if<boost::is_void< B >, void>::type void virtual process(A *, B *) = 0;
typename boost::enable_if<boost::is_void< B >, void>::type void virtual process(A *) = 0; };
struct Request { };
struct Response { };
typedef BaseListener<Response, void> BaseResponseListener; typedef BaseListener<Request, BaseResponseListener> BaseRequestListener;
struct RequestListener : public BaseRequestListener { void process(Request *, BaseResponseListener *) { } };
struct ResponseListener : public BaseResponseListener { void process(Request *) { } };
int main(int argc, char * argv[]) { RequestListener reqListener; ResponseListener resListener;
return 0; }
error message: error C2039: 'type' : is not a member of 'boost::enable_if<Cond,T>' 1> with 1> [ 1> Cond=boost::is_void<BaseResponseListener>, 1> T=void 1> ] 1> c:\!projects\temp\consoleeventhandler\consoleeventhandler.cpp(134) : see reference to class template instantiation 'BaseListener<A,B>' being compiled 1> with 1> [ 1> A=Request, 1> B=BaseResponseListener 1> ] -- View this message in context: http://www.nabble.com/boost%3A%3Aenable_if%2C-did-I-get-it-wrong---tp2502791... Sent from the Boost - Users mailing list archive at Nabble.com.
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