cleaning up interface, adding std_function example

example/std_function/example.cpp

@@ -0,0 +1,52 @@
+/*
+
+Copyright Barrett Adair 2015
+Distributed under the Boost Software License, Version 1.0.
+(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
+
+*/
+
+#include <cassert>
+#undef NDEBUG
+#include "make_function.hpp"
+
+using example::make_function;
+using namespace std::placeholders;
+
+int add(int i, int j) {
+    return i + j;
+}
+
+struct adder {
+
+    int eval(int i, int j) const {
+        return i + j;
+    }
+};
+
+void check_add(std::function<int(int, int)> f) {
+
+    auto add_result = f(99, 1);
+    assert(add_result == 100);
+}
+
+int main() {
+
+    //function pointer
+    auto f = make_function(&add);
+    check_add(f);
+
+    //function reference
+    f = make_function(add);
+    check_add(f);
+
+    //lambda
+    f = make_function([](int i, int j) {
+        return i + j;
+    });
+    check_add(f);
+
+    //member function pointer (bound to object)
+    f = make_function(&adder::eval, adder{}, _1, _2);
+    check_add(f);
+}