C++ 使 shared_ptr 不使用删除
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make shared_ptr not use delete
提问by Greg Domjan
in my code i would like boost::shared_ptr not to call delete but call ptr->deleteMe() instead.
在我的代码中，我希望 boost::shared_ptr 不调用 delete 而是调用 ptr->deleteMe() 。
Also i have a few C styled functions that return a ptr. Can i make it call lib_freeXYZ(ptr); instead of trying to delete?
我也有一些 C 风格的函数返回一个 ptr。我可以让它调用 lib_freeXYZ(ptr); 而不是试图删除？
回答by Greg Domjan
Or how about using the stl to provide the wrapper functor - Doug T. description but without the custom caller.
或者如何使用 stl 提供包装函子 - Doug T. 描述但没有自定义调用者。
boost::shared_ptr<T> ptr( new T, std::mem_fun_ref(&T::deleteMe) );
boost::shared_ptr<S> ptr( new S, std::ptr_fun(lib_freeXYZ) );
回答by Doug T.
You can give the shared_ptr template a custom deleter function which has the signature
您可以为 shared_ptr 模板提供具有签名的自定义删除器函数
void Deleter( T* ptr);
for a boost::shared_ptr
对于 boost::shared_ptr
So for Deleter you would do
所以对于 Deleter 你会做
boost::shared_ptr<T> ptrToT( new T, Deleter );
then in the body of Deleter:
然后在 Deleter 的正文中：
void Deleter( T* ptr);
{
ptr->deleteMe();
// And make sure YOU ACTUALLY DELETE (or do whatever else you need to
// do to release the resource)
delete ptr;
}
For your specific case when you need something simple (like ptr->deleteMe) see Greg's solution, its very nice.
对于您需要简单操作（如 ptr->deleteMe）的特定情况，请参阅 Greg 的解决方案，它非常好。
回答by Johannes Schaub - litb
Doug T.answered your question nicely. I'll tell you about intrusive_ptr. Maybe you can use it in your project too.
Doug T.很好地回答了你的问题。我会告诉你关于 intrusive_ptr 的。也许你也可以在你的项目中使用它。
If you have some C library that has already reference counting, but you have to manually call those functions, you can use boost::intrusive_ptrtoo, and provide proper definitions for its add_ref and release functions. intrusive_ptr will find and call them. They are responsible to increment the reference count and decrement it, freeing the resource when necassary:
如果你有一些已经有引用计数的 C 库，但你必须手动调用这些函数，你也可以使用boost::intrusive_ptr，并为其 add_ref 和 release 函数提供适当的定义。intrusive_ptr 会找到并调用它们。他们负责增加引用计数并减少它，在必要时释放资源：
void intrusive_ptr_add_ref(foo *f) {
lib_add_ref(f);
}
void intrusive_ptr_release(foo *f) {
if(lib_dec_ref(f) == 0)
lib_free(f);
}
Then you can just create objects from raw pointers of type foo*. intrusive_ptrwill call your functions when its copied/destructed:
然后你可以从类型的原始指针创建对象foo*。intrusive_ptr将在复制/销毁时调用您的函数：
intrusive_ptr<foo> f(lib_alloc());
// can wrap raw pointers too, which already may be referenced somewhere else
foo *p = get_foo_from_somewhere();
function_taking_intrusive_ptr(p);
回答by Kris Kumler
For the C-style data, do as @Doug. T suggested.
对于 C 样式数据，请按照@Doug 进行操作。T建议。
For your class, why not do cleanup in a destructor? Even if this is including deleteMe() in the destructor.
对于您的班级，为什么不在析构函数中进行清理？即使这在析构函数中包含 deleteMe() 。
