text: //   Copyright 2018 SiLeader and Cerussite.
  //
  //   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 "function.hpp"
  
  #include <iostream>
  
  namespace {
      struct f_obj {
          void operator()(int n)const {
              std::cout<<"function object "<<n<<std::endl;
          }
      };
      void f(int n) {
          std::cout<<"function "<<n<<std::endl;
      }
  } /* anonymouse */
  
  int main() {
      func::function<void(int)> vif;
  
      vif=[](int n){
          std::cout<<"lambda "<<n<<std::endl;
      };
      vif(2);
  
     vif = f_obj{};
     vif(3);
  
     vif = f;
     vif(4);
  
     return 0;
  }
  