目标:
我想要一个范围检查版本的 std::vector
的 operator []
用于我的调试版本,并且在发布模式下没有范围检查.>
调试模式下的范围检查显然有利于调试,但它会导致我希望避免的发布代码速度降低 5% - 10%.
可能的解决方案:
我在 Stroustrup 的C++ 编程语言"中找到了解决方案.他做了以下事情:
template 类checked_vector : public std::vector<T>{上市:使用 std::vector::vector;//用at()覆盖操作符[]};
这是有问题的,因为它继承自具有危险的非虚拟析构函数的类.(还有休息室 不太喜欢 喜欢那个解决方案.)
另一个想法是这样的类:
template 类checked_vector {std::vector数据_;上市://手工把所有 std::vector 的公共方法放在这里};
这既乏味又会产生大量的复制粘贴,这也很糟糕.
上述两种解决方案的好处是我可以简单地使用我的 makefile 中的宏定义来打开和关闭它们.
问题:
如果我没记错的话,这是 Visual Studio 的常见情况.使用 g++,您必须使用 -D_GLIBCXX_CONCEPT_CHECKS -D_GLIBCXX_DEBUG -D_GLIBCXX_DEBUG_PEDANTIC
调用编译器.(很可能你三个都不需要,但我都用了三系统.)与其他编译器,检查文档.这里标准中未定义行为的目的正是为了允许这种事情.
The goal:
I would like to have a range checked version of std::vector
's operator []
for my debug builds and no range check in release mode.
The range check in debug mode is obviously good for debugging, but it causes a slowdown of 5% - 10% in my release code which I would like to avoid.
Possible solutions:
I found a solution in Stroustrup's "The C++ programming language". He did the following:
template <class T>
class checked_vector : public std::vector<T> {
public:
using std::vector<T>::vector;
//override operator [] with at()
};
This is problematic because it inherits from a class with non-virtual destructor which is dangerous. (And the Lounge was not too fond of that solution.)
Another idea would be a class like this:
template <class T>
class checked_vector {
std::vector<T> data_;
public:
//put all public methods of std::vector here by hand
};
This would be both tedious and create a large amount of copy-paste which is bad too.
The nice thing about both the above solutions is that I can simply toggle them on and off with a macro definition in my makefile.
The questions:
If I'm not mistaken, this is the usual situation with Visual Studio. With g++, you have to invoke the compiler with -D_GLIBCXX_CONCEPT_CHECKS -D_GLIBCXX_DEBUG -D_GLIBCXX_DEBUG_PEDANTIC
. (It's probable that you don't need all three, but I use all
three systematically.) With other compilers, check the documentation. The purpose of the undefined behavior in the standard here is precisely to allow this sort of thing.
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