home | help 
std::bad_weak_ptr(3)	       C++ Standard Libary	    std::bad_weak_ptr(3)

NAME
     std::bad_weak_ptr - std::bad_weak_ptr

Synopsis
	Defined in header <memory>
	class bad_weak_ptr;	    (since C++11)

	std::bad_weak_ptr  is the type of the object thrown as exceptions by the
     constructors
	of std::shared_ptr that take std::weak_ptr as  the  argument,  when  the
     std::weak_ptr
	refers to an already deleted object.

	std-bad weak ptr-inheritance.svg

					Inheritance diagram

Member functions
	constructor   constructs a new bad_weak_ptr object
		      (public member function)
	operator=     replaces the bad_weak_ptr object
		      (public member function)
	what	      returns the explanatory string
		      (public member function)

     std::bad_weak_ptr::bad_weak_ptr

	bad_weak_ptr() noexcept;			    (1) (since C++11)
	bad_weak_ptr( const bad_weak_ptr& other ) noexcept; (2) (since C++11)

	Constructs  a  new  bad_weak_ptr  object  with an implementation-defined
     null-terminated
	byte string which is accessible through what().

	1) Default constructor.
	2)  Copy  constructor.	If  *this  and	other  both  have  dynamic  type
     std::bad_weak_ptr
	then std::strcmp(what(), other.what()) == 0.

Parameters
	other - another exception object to copy

     std::bad_weak_ptr::operator=

	bad_weak_ptr&  operator=(  const bad_weak_ptr& other ) noexcept;  (since
     C++11)

	Assigns the contents with those of other. If *this and other  both  have
     dynamic type
	std::bad_weak_ptr  then std::strcmp(what(), other.what()) == 0 after as-
     signment.

Parameters
	other - another exception object to assign with

Return value
	*this

     std::bad_weak_ptr::what

	virtual const char* what() const noexcept;  (since C++11)

	Returns the explanatory string.

Parameters
	(none)

Return value
	Pointer to a null-terminated string with  explanatory  information.  The
     string is
	suitable  for  conversion  and display as a std::wstring. The pointer is
     guaranteed to
	be valid at least until the exception object from which it  is	obtained
     is destroyed,
	or  until a non-const member function (e.g. copy assignment operator) on
     the
	exception object is called.

Notes
	Implementations are allowed but not required to override what().

     Inherited from std::exception

Member functions
	destructor   destroys the exception object
	[virtual]    (virtual public member function of std::exception)
	what	     returns an explanatory string
	[virtual]    (virtual public member function of std::exception)

Example
     // Run this code

      #include <iostream>
      #include <memory>

      int main()
      {
	  std::shared_ptr<int> p1(new int(42));
	  std::weak_ptr<int> wp(p1);
	  p1.reset();
	  try
	  {
	      std::shared_ptr<int> p2(wp);
	  }
	  catch (const std::bad_weak_ptr& e)
	  {
	      std::cout << e.what() << '\n';
	  }
      }

Possible output:
      std::bad_weak_ptr

	Defect reports

	The following behavior-changing defect	reports  were  applied	retroac-
     tively to
	previously published C++ standards.

	   DR	  Applied to	      Behavior as published		 Correct
     behavior
			    calling what on a default-constructed    the  return
     value is
	LWG 2376 C++11	    bad_weak_ptr was required to return      implementa-
     tion-defined
			    "bad_weak_ptr"

See also
	shared_ptr smart pointer with shared object ownership semantics
	(C++11)    (class template)
	weak_ptr   weak reference to an object managed by std::shared_ptr
	(C++11)    (class template)

http://cppreference.com 	   2024.06.10		    std::bad_weak_ptr(3)
home | help