1 files changed, 71 insertions, 0 deletions
diff --git a/libs/local_function/example/impl_tparam_tricks.cpp b/libs/local_function/example/impl_tparam_tricks.cpp
new file mode 100644
index 0000000000..aa394df2d8
--- /dev/null
+++ b/libs/local_function/example/impl_tparam_tricks.cpp
@@ -0,0 +1,71 @@
+
+// Copyright (C) 2009-2012 Lorenzo Caminiti
+// Distributed under the Boost Software License, Version 1.0
+// (see accompanying file LICENSE_1_0.txt or a copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+// Home at http://www.boost.org/libs/local_function
+
+//[impl_tparam_tricks
+#include <boost/detail/lightweight_test.hpp>
+#include <vector>
+#include <algorithm>
+
+// Casting functor trick.
+struct casting_func {
+    explicit casting_func(void* obj, void (*call)(void*, const int&))
+            : obj_(obj), call_(call) {}
+    // Unfortunately, function pointer call is not inlined.
+    inline void operator()(const int& num) { call_(obj_, num); }
+private:
+    void* obj_;
+    void (*call_)(void*, const int&);
+};
+
+// Virtual functor trick.
+struct virtual_func {
+    struct interface {
+        // Unfortunately, virtual function call is not inlined.
+        inline virtual void operator()(const int&) {}
+    };
+    explicit virtual_func(interface& func): func_(&func) {}
+    inline void operator()(const int& num) { (*func_)(num); }
+private:
+    interface* func_;
+};
+
+int main(void) {
+    int sum = 0, factor = 10;
+
+    // Local class for local function.
+    struct local_add : virtual_func::interface {
+        explicit local_add(int& _sum, const int& _factor)
+                : sum_(_sum), factor_(_factor) {}
+        inline void operator()(const int& num) {
+            body(sum_, factor_, num);
+        }
+        inline static void call(void* obj, const int& num) {
+            local_add* self = static_cast<local_add*>(obj);
+            self->body(self->sum_, self->factor_, num);
+        }
+    private:
+        int& sum_;
+        const int& factor_;
+        inline void body(int& sum, const int& factor, const int& num) {
+            sum += factor * num;
+        }
+    } add_local(sum, factor);
+    casting_func add_casting(&add_local, &local_add::call);
+    virtual_func add_virtual(add_local);
+
+    std::vector<int> v(10);
+    std::fill(v.begin(), v.end(), 1);
+    
+    // std::for_each(v.begin(), v.end(), add_local); // Error but OK on C++11.
+    std::for_each(v.begin(), v.end(), add_casting); // OK.
+    std::for_each(v.begin(), v.end(), add_virtual); // OK.
+
+    BOOST_TEST(sum == 200);
+    return boost::report_errors();
+}
+//]
+