1 // Copyright 2019 The Marl Authors. 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // https://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 #ifndef marl_defer_h 16 #define marl_defer_h 17 18 #include "finally.h" 19 20 namespace marl { 21 22 #define MARL_CONCAT_(a, b) a##b 23 #define MARL_CONCAT(a, b) MARL_CONCAT_(a, b) 24 25 // defer() is a macro to defer execution of a statement until the surrounding 26 // scope is closed and is typically used to perform cleanup logic once a 27 // function returns. 28 // 29 // Note: Unlike golang's defer(), the defer statement is executed when the 30 // surrounding *scope* is closed, not necessarily the function. 31 // 32 // Example usage: 33 // 34 // void sayHelloWorld() 35 // { 36 // defer(printf("world\n")); 37 // printf("hello "); 38 // } 39 // 40 #define defer(x) \ 41 auto MARL_CONCAT(defer_, __LINE__) = marl::make_finally([&] { x; }) 42 43 } // namespace marl 44 45 #endif // marl_defer_h 46