-----Original Message----- From: Boost [mailto:boost-bounces@lists.boost.org] On Behalf Of Bjorn Reese Sent: 05 July 2015 17:06 To: boost@lists.boost.org Subject: Re: [boost] Ternary logic programming
On 07/05/2015 12:10 PM, Rob Stewart wrote:
That might be legitimate, and even useful, but doesn't it seem wrong that && and || yield the same results?
The three cases under discussion may be easier to understand if we look at their Venn diagrams, so I have drawn them here:
http://breese.github.io/2015/07/05/layers-of-three-valued-logic.html
(the text could be more elaborate, but I wanted to make the diagrams available as quickly as possible.)
If the empty state is called the same thing in each case, different behavior will be confusing. Otherwise, I agree that forcing everything into the same pattern may be more trouble than it's worth.
Indeed. The empty state may have to be called different names for the three alternatives.
Nice! Can this be added to the tribool docs - it might avoid confusion and discussion on future Boost lists. Might some MetaMagic allow the user to provide a compile-time template parameter to choose if wants tribool truth-table to be either 'don't, may, or do care'? But provide a default to keep the behaviour as now? Paul --- Paul A. Bristow Prizet Farmhouse Kendal UK LA8 8AB +44 (0) 1539 561830