Go-like defer in C++

defer_with_example.cpp

#include <iostream>
#include <string>

namespace impl {
  template <typename Fun> struct DeferredWrapper
  { 
    Fun f_;
    DeferredWrapper(Fun &&f) : f_{std::forward<Fun>(f)} {}
    ~DeferredWrapper() {
      f_();
    }
  };
}

template <typename Fun>
auto on_scope_exit(Fun &&f) {
  return impl::DeferredWrapper<Fun>{std::forward<Fun>(f)};
}

// example of usage
void foo() {
  std::cout << "on entry" << std::endl;
  
  std::string s = "on exit";
  auto _ = on_scope_exit([&](){ std::cout << s << std::endl;});

  std::cout << "middle" << std::endl;
}