unique_ptr <T>用于数组特化的lambda自定义删除器

Question

我最近开始将大量现有的C++应用程序代码移植到C++ 11,现在我转换为新的智能指针std :: unique_ptr和std :: shared_ptr,我有一个关于自定义删除的具体问题.我想添加一个lambda记录器来查看我的删除被调用的位置但是我无法获得要编译的数组特化版本.建议将非常感谢.

我已经白白被搜索用于阵列专业化一个定制删除的一个例子的unique_ptr为VC++ 10或GCC 4.5.2+.我想在lambda中调用删除器时打印一条日志消息 - 主要是为了确保我认为超出范围的所有指针都这样做.这可能是专业化的阵列版本吗？我可以使用非数组版本,如果我将外部结构"MyArrayDeleter"作为第二个参数传递,我也可以使用数组特化.还有一件事,是否有可能删除丑陋的std :: function,因为我认为我可以让lambda签名数字出来.

struct MySimpleDeleter {
    void operator()(int* ptr) const {
        printf("Deleting int pointer!\n");
        delete ptr;
    }
};
struct MyArrayDeleter {
    void operator()(int* ptr) const {
        printf("Deleting Array[]!\n");
        delete [] ptr;
    }
};
{
    // example 1 - calls MySimpleDeleter where delete simple pointer is called
    std::unique_ptr<int, MySimpleDeleter> ptr1(new int(5));

    // example 2 - correctly calls MyArrayDeleter where delete[] is called
    std::unique_ptr<int[], MyArrayDeleter> ptr2(new int[5]);

    // example 3 - this works (but default_delete<int[]> would have been passed
    // even if I did not specialize it as it is the default second arg
    // I only show it here to highlight the problem I am trying to solve
    std::unique_ptr<int[], std::default_delete<int[]>> ptr2(new int[100]);

    // example 3 - this lambda is called correctly - I want to do this for arrays
    std::unique_ptr<int, std::function<void (int *)>> ptr3(
        new int(3), [&](int *ptr){ 
            delete ptr; std::cout << "delete int* called" << std::endl; 
        });

    // example 4 - I cannot get the following like to compile
    // PLEASE HELP HERE - I cannot get this to compile
    std::unique_ptr<int[], std::function<void (int *)>> ptr4(
        new int[4], [&](int *ptr){  
            delete []ptr; std::cout << "delete [] called" << std::endl; 
        });
}

The compiler error is as follows:

The error from the compiler (which complains about the new int[4] for ptr4 below is:
'std::unique_ptr<_Ty,_Dx>::unique_ptr' : cannot access private member declared in class 'std::unique_ptr<_Ty,_Dx>'
1>          with
1>          [
1>              _Ty=int [],
1>              _Dx=std::tr1::function<void (int *)>
1>          ]
1>          c:\program files (x86)\microsoft visual studio 10.0\vc\include\memory(2513) : see declaration of 'std::unique_ptr<_Ty,_Dx>::unique_ptr'
1>          with
1>          [
1>              _Ty=int [],
1>              _Dx=std::tr1::function<void (int *)>
1>          ]

Answer 1

关于什么:

auto deleter=[&](int* ptr){...};
std::unique_ptr<int[], decltype(deleter)> ptr4(new int[4], deleter);