C ++ 11 scope exit guard，一个好主意？

问题描述

我为C ++ 11编写了一个小实用程序类，我将其用作范围保护，以更容易处理异常安全和类似的事情。

I've written a small utility class for C++11 which I use as a scope guard for easier handling of exception safety and similar things.

似乎有点像一个黑客。但我很惊讶，我没有看到它在其他地方使用C ++ 11功能。我认为boost有类似的C ++ 98。

Seems somewhat like a hack. But I'm suprised I haven't seen it somewhere else using C++11 features. I think boost has something similar for C++98.

但是这是一个好主意吗？还是有我错过的潜在问题？是否已经有一个类似的解决方案（与C ++ 11功能）在boost或类似？

But is it a good idea? Or are there potential problems I have missed? Is there already a similar solution (with C++11 features) in boost or similar?

    namespace detail
    {
        template<typename T>
        class scope_exit : boost::noncopyable
        {
        public:
            explicit scope_exit(T&& exitScope) : exitScope_(std::forward<T>(exitScope)){}
            ~scope_exit(){try{exitScope_();}catch(...){}}
        private:
            T exitScope_;
        };

        template <typename T>
        scope_exit<T> create_scope_exit(T&& exitScope)
        {
            return scope_exit<T>(std::forward<T>(exitScope));
        }
    }


#define _UTILITY_EXIT_SCOPE_LINENAME_CAT(name, line) name##line
#define _UTILITY_EXIT_SCOPE_LINENAME(name, line) _UTILITY_EXIT_SCOPE_LINENAME_CAT(name, line)
#define UTILITY_SCOPE_EXIT(f) const auto& _UTILITY_EXIT_SCOPE_LINENAME(EXIT, __LINE__) = ::detail::create_scope_exit(f)

。

int main ()
{
  ofstream myfile;
  myfile.open ("example.txt");
  UTILITY_SCOPE_EXIT([&]{myfile.close();}); // Make sure to close file even in case of exception
  myfile << "Writing this to a file.\n"; // Imagine this could throw
  return 0;
}

推荐答案

当然。相关主题是。

您不处理异常。

Alexandrescu长时间想出了。 Boost和 std :: tr1 都有一个名为和（使用自定义删除程序），可以让您完成此操作。

Alexandrescu came up with ScopeGuard a long time back. Both Boost and std::tr1 has a thing called scoped_ptr and shared_ptr (with a custom deleter) that allows you to accomplish just this.

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