unique_ptr与期望原始指针的API？ [英] unique_ptr with an API that expects raw pointers?

问题描述

在使用托管内存和函数语言大约10年后，我终于回到了C ++，智能指针使我感到困惑。一半的文档仍然是关于弃用的 auto_ptr 。

我试图实现这个相当简单项目符号，但我要假装有一个原因...

After about 10 years of using managed memory and functional languages, I'm finally coming home to C++, and smart pointers are confusing the heck out of me. Half of the documentation out there is still regarding the deprecated auto_ptr.

I'm trying to implement this fairly straightforward Bullet "hello world" program:

int _tmain(int argc, _TCHAR* argv[])
{
    auto bp = unique_ptr<btBroadphaseInterface>(new btDbvtBroadphase);
    auto cc = unique_ptr<btDefaultCollisionConfiguration>(new btDefaultCollisionConfiguration);
    auto disp = unique_ptr<btDispatcher>(new btCollisionDispatcher(cc));
}

The btCollisionDispatcher constructor wants a btCollisionConfiguration*, but I'm giving it a unique_ptr to one instead.

What do I normally want to do in this case? If there's a way to "de-smart" the pointer, something tells me that unique_ptr isn't the right smart pointer to use.

C++ was my language of choice before I moved to other things. It's a little shocking coming back and seeing that all the patterns and practices have completely changed.

解决方案

There is a get() member function that gives you the raw pointer that is held by the unique_ptr. This does not cause the unique_ptr to relinquish the ownership, though, so proper cleanup will still happen (careful with storing that raw pointer!).

There is also a release() member function, which relinquishes ownership. This means that you're back on dumb pointer land and cleanup is all your responsibility.

I can't fathom why the code is using new in the first place and not just using automatic storage objects, but I'm going to pretend there is a reason...

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