理解了aliasing constructor之后,shared_pointer::owner_before()就更好理解了;(参考https://www.zhihu.com/question/24816143) 在标准库的shared_ptr中,operator<,比较的是stored pointer,因此上面举例的那种情况,p9和obj两个shared_ptr是不相等的;而owner
share_ptr 的 aliasing constructor: 可以使得share_ptr 拥有某个对象控制权的时候,存储指针(storage pointer,shared_ptr 还有一个概念叫owned ptr 指向存储当前控制对象相关信息)指向另外一个对象,模板如下: template <class U> shared_ptr (const shared_ptr<U>& x, element_type* p) noexcept; 该构造函数是的...
让你好好体会一下，“The object does not own p ”意思：// shared_ptr constructor example#include...
I've tracked this down and it appears that class_::init_holder (variant 1) will use shared_from_this() to initialize a holder in this case. The returned pointer created with the aliasing constructor is just immediately destroyed in favor of the one from shared_from_this(). Removing that ...
shared_ptr<_RawYp>(*this, const_cast<_RawYp*>(static_cast<const _Yp*>(__ptr))) 这个调用的是std::shared_ptr的别名构造函数(The aliasing constructor),意思是说,共享 r 参数的引用计数, 但是.get()返回的是 ptr 指针。 template< class Y > shared_ptr( const shared_ptr<Y>& r, element_ty...
The managed pointer is the one passed to the deleter when use count reaches zero. A shared_ptr may also own no objects, in which case it is called empty (an empty shared_ptr may have a non-null stored pointer if the aliasing constructor was used to create it). All specializations ...
http://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#discussion-use-a-factory-function-if-you-need-virtual-behavior-during-initialization uses std::make_shared() to construct shared pointer to derived class. I think std::make_shared() cannot be used here since the constructor of the ...
("Shared pointer: ", pShared); // compiler erroroutput("Shared pointer: ",&*pShared);// OK, calls operator*, then takes addroutput("Shared pointer with get(): ", pShared.get());delete pInt;std::cout<<"\nThe shared_ptr's aliasing constructor demo.\n";structBase1{inti1{};};...
boost::detail::sp_pointer_construct( this, p, pn ); } // // Requirements: D's copy constructor must not throw // // shared_ptr will release p by calling d(p) // template<class Y, class D> shared_ptr( Y * p, D d ): px( p ), pn( p, d ) ...
An empty shared_ptr (whereuse_count()==0) may store a non-null pointer accessible byget(), e.g. if it were created using the aliasing constructor. Example Run this code #include <iostream>#include <memory>voidreport(std::shared_ptr<int>ptr){if(ptr)std::cout<<"*ptr="<<*ptr<<"...