std::exception_ptr
| Defined in header <exception>
|
||
| typedef /*unspecified*/ exception_ptr; |
(since C++11) | |
std::exception_ptr is a nullable pointer-like type that manages an exception object which has been thrown and captured with std::current_exception. An instance of std::exception_ptr may be passed to another function, possibly on another thread, where the exception may be rethrown and handled with a catch clause.
Default-constructed std::exception_ptr is a null pointer, it does not point to an exception object.
Two instances of std::exception_ptr compare equal only if they are both null or both point at the same exception object.
std::exception_ptr is not implicitly convertible to any arithmetic, enumeration, or pointer type. It is convertible to bool.
The exception object referenced by an std::exception_ptr remains valid as long as there remains at least one std::exception_ptr that is referencing it: std::exception_ptr is a shared-ownership smart pointer.
Example
#include <exception> #include <iostream> #include <stdexcept> #include <string> void handle_eptr(std::exception_ptr eptr) // passing by value is OK { try { if (eptr) std::rethrow_exception(eptr); } catch(const std::exception& e) { std::cout << "Caught exception: '" << e.what() << "'\n"; } } int main() { std::exception_ptr eptr; try { [[maybe_unused]] char ch = std::string().at(1); // this generates a std::out_of_range } catch(...) { eptr = std::current_exception(); // capture } handle_eptr(eptr); } // destructor for std::out_of_range called here, when the eptr is destructed
Possible output:
Caught exception: 'basic_string::at: __n (which is 1) >= this->size() (which is 0)'
