+#include "internal_config.h"
+
+#ifdef LIBSIGC
+#include <sigc++/sigc++.h>
+#define surf_callback(arg1, ...) sigc::signal<arg1,__VA_ARGS__>
+#define surf_callback_connect(callback, fun_ptr) callback.connect(sigc::ptr_fun(fun_ptr))
+#define surf_callback_emit(callback, ...) callback.emit(__VA_ARGS__)
+#else
+#include <boost/signals2.hpp>
+#define surf_callback(arg1, ...) boost::signals2::signal<arg1(__VA_ARGS__)>
+#define surf_callback_connect(callback, fun_ptr) callback.connect(fun_ptr)
+#define surf_callback_emit(callback, ...) callback(__VA_ARGS__)
+#endif