Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

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

NAME
       std::exception_ptr - std::exception_ptr

Synopsis
	  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.

	  A 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 contextually convertible to bool,	and will eval-
       uate to false if
	  it is	null, true otherwise.

	  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 (note; this
       is in addition to
	  the usual exception object lifetime rules)

	  std::exception_ptr meets the requirements of NullablePointer.

Example
       // Run this code

	#include <iostream>
	#include <string>
	#include <exception>
	#include <stdexcept>

	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	{
		std::string().at(1); //	this generates an 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"

See also
	  make_exception_ptr  creates  an std::exception_ptr from an exception
       object
	  (C++11)	     (function template)
	  current_exception  captures the current exception in	a  std::excep-
       tion_ptr
	  (C++11)	     (function)
	  rethrow_exception  throws the	exception from an std::exception_ptr
	  (C++11)	     (function)

http://cppreference.com		  2022.07.31		 std::exception_ptr(3)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=std::exception_ptr&sektion=3&manpath=FreeBSD+Ports+15.0>

home | help