Le 28/06/12 22:16, Emil Dotchevski a écrit :

On Thu, Jun 28, 2012 at 10:42 AM, Brian Wood<woodbrian77@gmail.com> wrote:

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I haven't found much on use cases in single threaded programs. Do you have any links? I did find the following comment in some code that uses exception_ptr.

Any time when a failure can't be handled at the time it is reported, which usually involves asynchronous operations, which usually involves multiple threads.

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"The reason here is that construction/destruction of an exception_ptr are not "cheap""

Calling boost::throw_exception doesn't construct or destruct exception_ptr objects. Any use of boost::exception_ptr requires #including <boost/exception_ptr.hpp>.

Does the use of BOOST_THROW_EXCEPTION implies the use of exception_ptr? Best, Vicente

Le 29/06/12 09:17, Emil Dotchevski a écrit :

On Thu, Jun 28, 2012 at 11:53 PM, Vicente J. Botet Escriba< vicente.botet@wanadoo.fr> wrote:

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Does the use of BOOST_THROW_EXCEPTION implies the use of exception_ptr?

BOOST_THROW_EXCEPTION simply captures information about the throw location, then calls boost::throw_exception.

I see that template<class E> BOOST_ATTRIBUTE_NORETURN inline void throw_exception( E const & e ) { //All boost exceptions are required to derive from std::exception, //to ensure compatibility with BOOST_NO_EXCEPTIONS. throw_exception_assert_compatibility(e); #ifndef BOOST_EXCEPTION_DISABLE throw enable_current_exception(enable_error_info(e)); #else throw e; #endif } From the documentation, enable_current_exception let me think that we not only BOOST_THROW_EXCEPTION but boost::throw_exception immplies the use of exception_ptr, isn't it? Am I missing something evident? Best, Vicente enable_current_exception #include <boost/exception/enable_current_exception.hpp> namespace boost { template<class T> ---unspecified---enable_current_exception( T const& e ); } Requirements: * T must be a class with an accessible no-throw copy constructor. * If T has any virtual base types, those types must have an accessible default constructor. Returns: An object of /unspecified/ type which derives publicly from T. That is, the returned object can be intercepted by a catch(T &). Description: This function is designed to be used directly in a throw-expression to enable the exception_ptr support in Boost Exception. For example: class my_exception: public std::exception { }; .... throw boost::enable_current_exception(my_exception()); Unless enable_current_exception is called at the time an exception object is used in a throw-expression, an attempt to copy it using current_exception may return an exception_ptr which refers to an instance of unknown_exception. See current_exception for details. Note: Instead of using the throw keyword directly, it is preferable to call boost::throw_exception. This is guaranteed to throw an exception that derives from boost::exception and supports the exception_ptr functionality.