std::bad_weak_ptr
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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 ofstd::shared_ptr that takestd::weak_ptr as the argument, when thestd::weak_ptr refers to an already deleted object.
Inheritance diagram
Contents |
[edit]Member functions
(constructor) | constructs a newbad_weak_ptr object(public member function) |
operator= | replaces thebad_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 newbad_weak_ptr object with an implementation-defined null-terminated byte string which is accessible throughwhat().
std::bad_weak_ptr thenstd::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 ofother. If*this andother both have dynamic typestd::bad_weak_ptr thenstd::strcmp(what(), other.what())==0 after assignment.
Parameters
| other | - | another exception object to assign with |
Return value
*this
std::bad_weak_ptr::what
virtualconstchar* what()constnoexcept; | (since C++11) | |
Returns the explanatory string.
Return value
Pointer to an implementation-defined null-terminated string with explanatory information. The string is suitable for conversion and display as astd::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 overridewhat().
Inherited fromstd::exception
Member functions
[virtual] | destroys the exception object (virtual public member function of std::exception)[edit] |
[virtual] | returns an explanatory string (virtual public member function of std::exception)[edit] |
[edit]Example
#include <iostream>#include <memory> int main(){std::shared_ptr<int> p1(newint(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
[edit]Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| LWG 2376 | C++11 | callingwhat on a default-constructedbad_weak_ptr was required to return"bad_weak_ptr" | the return value is implementation-defined |
[edit]See also
(C++11) | smart pointer with shared object ownership semantics (class template)[edit] |
(C++11) | weak reference to an object managed bystd::shared_ptr (class template)[edit] |
