获取一个boost :: shared_ptr的这个 [英] Getting a boost::shared_ptr for this

问题描述

我正在广泛使用升压的：在我的code的shared_ptr 。事实上，大多数在堆中分配的对象是由的shared_ptr 举行。不幸的是，这意味着我无法通过这个成需要一个的shared_ptr 任何功能。考虑这个code：

I am making extensive use of boost:shared_ptr in my code. In fact, most of the objects that are allocated on the heap are held by a shared_ptr. Unfortunately this means that I can't pass this into any function that takes a shared_ptr. Consider this code:

void bar(boost::shared_ptr<Foo> pFoo)
{
    ...
}

void Foo::someFunction()
{
    bar(this);
}

这里有两个问题。首先，这将不会编译，因为T *构造的shared_ptr 是明确的。其次，如果我强迫它来建立与巴（提高:: shared_ptr的＆LT;富＆GT;（本））我将创建第二个共享指针，以我的对象，最终将导致以双删除。

There are two problems here. First, this won't compile because the T* constructor for shared_ptr is explicit. Second, if I force it to build with bar(boost::shared_ptr<Foo>(this)) I will have created a second shared pointer to my object that will eventually lead to a double-delete.

这使我想到我的问题：有没有得到任何标准模式从这些对象的一个​​方法中存在，你知道现有的共享指针的副本？采用侵入式引用计数在这里我唯一的选择？

This brings me to my question: Is there any standard pattern for getting a copy of the existing shared pointer you know exists from inside a method on one of those objects? Is using intrusive reference counting my only option here?

推荐答案

您可以从<一个派生href=\"http://www.boost.org/doc/libs/1_36_0/libs/smart_ptr/enable_shared_from_this.html\">enable_shared_from_this然后你可以使用shared_from_this（）而不是本，以一个共享指针产卵到你自己的对象。

You can derive from enable_shared_from_this and then you can use "shared_from_this()" instead of "this" to spawn a shared pointer to your own self object.

实例链接：

#include <boost/enable_shared_from_this.hpp>

class Y: public boost::enable_shared_from_this<Y>
{
public:

    shared_ptr<Y> f()
    {
        return shared_from_this();
    }
}

int main()
{
    shared_ptr<Y> p(new Y);
    shared_ptr<Y> q = p->f();
    assert(p == q);
    assert(!(p < q || q < p)); // p and q must share ownership
}

这是（），而这是一个好主意，当从一个成员函数产卵线程的boost ::绑定到shared_from_this。它将确保对象不会被释放。

It's a good idea when spawning threads from a member function to boost::bind to a shared_from_this() instead of this. It will ensure that the object is not released.

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