-----Original Message----- From: boost-bounces@lists.boost.org [mailto:boost-bounces@lists.boost.org] On Behalf Of joel Sent: 14 August 2009 17:46 To: boost@lists.boost.org Subject: Re: [boost] different matrix library?
You should have one matrix class whose tempalte parameters allow for customization. Want a matrix with static data : matrix<float, settings<static_> >
This is a really good idea - but can appear (and be!) quite complicated - if you want an example of policies and their use, you might like to look at the documentation (and the source code later) of John Maddock's Boost Math Toolkit. In the Math Toolkit, a template parameter allows one to control what happens when a math function call causes trouble - like going to infinity. You can choose to return std::numeric_limits infinity, or max, throw an exception, define your own special policy even, or ignore it completely. All the options have some merit. The most popular is chosen as the default for the math function. If users don't care, or don't understand policies, they get the default - which is hopefully what they wanted anyway. Users still have fine-grained choice that is quite easy to use. The downside is that it badly obscures the source code to readers and is a whole lot of work to implement for the writer. And even more trouble to test - even corner cases mount up horribly. Documenting it takes yet more effort. Finally maintenance later is made more difficult. It may be best to add policies when the code is reasonably stable for what you guess is the default? Good luck. Paul --- Paul A. Bristow Prizet Farmhouse Kendal, UK LA8 8AB +44 1539 561830, mobile +44 7714330204 pbristow@hetp.u-net.com