owner_before() 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
让你好好体会一下，“The object does not own p ”意思：// shared_ptr constructor example#include...
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...
A returned std::shared_ptr created via the "aliasing constructor" gets lost when the class inherits from std::enable_shared_from_this. 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 return...
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 of shared_ptr meet the requirements of CopyConstructible, CopyAssignable, and LessThan...
8)Thealiasing constructor: constructs ashared_ptrwhich shares ownership information with the initial value ofr, but holds an unrelated and unmanaged pointerptr. If thisshared_ptris the last of the group to go out of scope, it will call the stored deleter for the object originally managed byr....
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...
());delete pInt;std::cout<<"\nThe shared_ptr's aliasing constructor demo.\n";structBase1{inti1{};};structBase2{inti2{};};structDerived:Base1, Base2{inti3{};};std::shared_ptr<Derived>p(new Derived());std::shared_ptr<Base2>q(p,static_cast<Base2*>(p.get()));std::cout<...
explicit shared_ptr( Y * p ): px( p ), pn() // Y must be complete { 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) ...
An empty shared_ptr (where use_count() == 0) may store a non-null pointer accessible by get(), e.g. if it were created using the aliasing constructor. ExampleRun this code #include <iostream> #include <memory> void report(std::shared_ptr<int> ptr) { if (ptr) std::cout << "...