iox-eclipse-iceoryx#391 cleanup and restructuring of storable_function

Signed-off-by: Matthias Killat <matthias.killat@apex.ai>

iceoryx_utils/include/iceoryx_utils/cxx/function.hpp

@@ -0,0 +1,46 @@
+// Copyright (c) 2020 by Apex.AI Inc. All rights reserved.
+//
+// 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.
+
+#ifndef IOX_UTILS_FUNCTION_HPP
+#define IOX_UTILS_FUNCTION_HPP
+
+#include "iceoryx_utils/internal/cxx/static_storage.hpp"
+#include "iceoryx_utils/internal/cxx/storable_function.hpp"
+
+namespace iox
+{
+namespace cxx
+{
+/// @note set the storage type and reorder template arguments for the user API
+/// the storage type must precede the (required) variadic arguments in the internal one
+/// if the static storage is insufficient to store the callable we get a compile time error
+
+/// @note this alias is needed to improve usability
+///       for the API see storable_function
+template <typename Signature, uint64_t Bytes = 128>
+using function = storable_function<static_storage<Bytes>, Signature>;
+
+/// @note the following would essentially be a complete std::function replacement
+/// which would allocate dynamically if the static storages of Bytes is not sufficient
+/// to store the callable (i.e. we use an optimized_storage)
+// template <typename Signature, uint64_t Bytes = 128>
+// using function = detail::storable_function<optimized_storage<Bytes>, Signature>;
+// or alternatively
+// template <typename Signature>
+// using function = detail::storable_function<dynamic_storage, Signature>;
+
+} // namespace cxx
+} // namespace iox
+
+#endif // IOX_UTILS_FUNCTION_HPP