more thoughts

NextGen.cpp

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+
+/**
+ * Copyright 2015-2016 Denis Blank <denis.blank@outlook.com>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <tuple>
+#include <type_traits>
+#include <string>
+
+namespace detail {
+  template<typename... T>
+  struct Identity { };
+
+  template<typename T, typename... Rest>
+  struct IdentityInheritenceWrapper
+    : Identity<T>, IdentityInheritenceWrapper<Rest...> { };
+
+  enum class NamedParameterId {
+    NAMED_PARAMATER_CALLBACK,
+    NAMED_PARAMATER_REJECTOR
+  };
+
+  template <NamedParameterId Value, typename T>
+  struct NamedParameter
+    : std::integral_constant<NamedParameterId, Value>,
+      std::common_type<T> { };
+
+  template <NamedParameterId Value, typename Default, typename... Args>
+  using GetNamedParameterOrDefault = void;
+
+  template<typename, typename>
+  class ContinuableBase;
+
+  template<typename T>
+  struct ReturnTypeToContinuableConverter;
+
+  template<typename... Args>
+  struct 
+
+  template<typename... Args, typename CallbackType>
+  class ContinuableBase<Identity<Args...>, typename CallbackType> {
+    CallbackType callback_;
+
+  public:
+    explicit ContinuableBase(CallbackType&& callback)
+      : callback_(std::move(callback)) { }
+
+    template<typename C>
+    auto then(C&& continuation) {
+      // The type the callback will evaluate to
+      using EvaluatedTo = decltype(std::declval<C>()(std::declval<Args>()...));
+
+
+      return EvaluatedTo{ };
+    }
+  };
+} // namespace detail
+
+using namespace detail;
+
+template<typename... Args>
+using Continuable = detail::ContinuableBase<detail::Identity<Args...>>;
+
+template <typename... Args>
+struct Callback {
+  void operator() (Args... ) { }
+};
+
+template <typename... Args>
+auto make_continuable(Args&&...) {
+  return Continuable<> { };
+}
+
+auto http_request(std::string url) {
+  return make_continuable([url](auto&& callback) {
+
+    callback("<br>hi<br>");
+  });
+}
+
+void testNextGen() {
+  using t = GetNamedParameterOrDefault<
+    NamedParameterId::NAMED_PARAMATER_CALLBACK,
+    Identity<>,
+    void,
+    int,
+    NamedParameter<NamedParameterId::NAMED_PARAMATER_CALLBACK, std::string>,
+    float
+  >;
+
+  http_request("github.com")
+    .then([](std::string content) {
+      
+      return 
+    })
+    .then([] {
+
+    });
+}