-----Original Message----- From: boost-bounces@lists.boost.org [mailto:boost-bounces@lists.boost.org] On Behalf Of Matthias Schabel Sent: 02 May 2007 19:30 To: boost@lists.boost.org; boost-announce; boost-users Subject: [boost] [math toolkit] Review results
1) Error handling is an issue that arises because this library is at the frontier between traditional numerical libraries and a (hopefully) new breed of such libraries that utilize modern programming techniques and facilities. Jeff Garland suggested that the default behavior should be to throw an exception, with errno being an option enabled by macro.
Given a macro #define BOOST_MATH_THROW_ON_ALL_ERRORS to switch all the macros 'on' it would seem easy enough to switch to C++ exception handling state. I am unclear why the default should be one way or the other, and it's a hassle to change it, so I propose to leave as is.
It would also be nice to have more granular control over which instances throw exceptions and which do not (so, for example, a user could choose to ignore denormals).
\tools\error_handling.hpp appears to me to provide control, for example, of denormals though BOOST_MATH_THROW_ON_DENORM_ERROR If BOOST_MATH_THROW_ON_DENORM_ERROR is not defined, then errno is NOT set, so it is effectively ignored. We don't have a std exception type for denorming, so underflow_error is used instead.
It was also suggested that additional, more transparent exceptions be provided for cases such as failure to converge rather than reusing tools::logic_error.
The standard exception classes seem rather ill-defined (ill-conceived even?) to me and I can't see a standard exception that fits the bill for 'failed to converge'. "failed to converge" seems a run-time error, so would std::range_error, be the least unsuitable (neither under nor overflow_error seem right)? Or does anyone have a better suggestion? Paul --- Paul A Bristow Prizet Farmhouse, Kendal, Cumbria UK LA8 8AB +44 1539561830 & SMS, Mobile +44 7714 330204 & SMS pbristow@hetp.u-net.com