select 2nd element in pair

src/FbTk/Select2nd.hh

@@ -0,0 +1,18 @@
+#ifndef FBTK_SELECT2ND_HH
+#define FBTK_SELECT2ND_HH
+
+#include <functional>
+
+namespace FbTk {
+
+template <class A>
+class Select2nd:public std::unary_function<A, typename A::second_type> {
+public:
+    typename A::second_type operator () (const A &arg) const {
+        return arg.second;
+    }
+};
+
+} // namespace FbTk
+
+#endif // FBTK_SELECT2ND_HH