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According to N3290, std::unique_ptr accepts a deleter argument in its constructor.
However, I can't get that to work with Visual C++ 10.0 or MinGW g++ 4.4.1 in Windows, nor with g++ 4.6.1 in Ubuntu.
I therefore fear that my understanding of it is incomplete or wrong. I can't see the point of a deleter argument that's apparently ignored, so can anyone provide a working example?
Preferably I'd like to see also how that works for unique_ptr<Base> p = unique_ptr<Derived>( new Derived ).
Possibly with some wording from the standard to back up the example, i.e. that with whatever compiler you're using, it actually does what it's supposed to do?
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unique_ptr objects automatically delete the object they manage (using a deleter) as soon as they themselves are destroyed, or as soon as their value changes either by an assignment operation or by an explicit call to unique_ptr::reset.
A unique_ptr does not share its pointer. It cannot be copied to another unique_ptr , passed by value to a function, or used in any C++ Standard Library algorithm that requires copies to be made. A unique_ptr can only be moved.
std::unique_ptr is a smart pointer that owns and manages another object through a pointer and disposes of that object when the unique_ptr goes out of scope. The object is disposed of, using the associated deleter when either of the following happens: the managing unique_ptr object is destroyed.
std::unique_ptr::resetDestroys the object currently managed by the unique_ptr (if any) and takes ownership of p. If p is a null pointer (such as a default-initialized pointer), the unique_ptr becomes empty, managing no object after the call.
This works for me in MSVC10
int x = 5; auto del = [](int * p) { std::cout << "Deleting x, value is : " << *p; }; std::unique_ptr<int, decltype(del)> px(&x, del); And on gcc 4.5, here
I'll skip going to the standard, unless you don't think that example is doing exactly what you'd expect it to do.
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