A macro/template implementation of C++ scope guard

scope_exit.hxx

#pragma once

#include <utility>

namespace ScopeExitNamespace__ {
  template<typename T> struct OnScopeExit__ {
    T func;
    OnScopeExit__(T func) : func(std::move(func)) {}
    ~OnScopeExit__() noexcept { func(); }
  };
}

#define scope_exit__(id, code) \
  auto scope_exit_function_##id##__ = [&](){code;}; \
  ScopeExitNamespace__::OnScopeExit__<decltype(scope_exit_function_##id##__)> \
    scope_exit_cleanup_##id##__(std::move(scope_exit_function_##id##__))

#define scope_exit(code) scope_exit__(__COUNTER__, code)

// #include <iostream>
// int main()
// {
//   scope_exit(std::cout << "done" << std::endl);
//   std::cout << "Running...";
//   return 0;
// }