Hi John,
thanks again for all the questions. I am breaking up the long posting
into smaller portions.
(1) Representation of single elements with statically bounded intervals:
2011/2/23 John Reid
On 22/02/11 20:03, Joachim Faulhaber wrote:
2011/2/22 John Reid
I have started to use statically bounded intervals and am finding more compilation issues. For example with finding elements in a map:
#define BOOST_ICL_USE_STATIC_BOUNDED_INTERVALS #include
void f() { namespace icl = ::boost::icl; icl::interval_map< float, int>().find( 0 ); }
This compiles without the #define but fails on static intervals.
This is on purpose. The reason is that we can not represent a single element x using a right-open interval [x,?) of continuous values. right_open_interval is the default for statically bounded intervals, if BOOST_ICL_USE_STATIC_BOUNDED_INTERVALS is defined. In order to use find on an interval_map we have to construct an interval that represents a single element (internally). This is not possible in the logic of the ICL so this code won't compile.
Nevertheless, users will expect to be able to locate elements in sets. How should they do this?
they could use dynamically bounded intervals for continuous interval element types :P Moreover, if we work with floating point numbers, the code float pi = 3.14159 ... ; icl::interval_set<float> icl_float_set = ... ; icl::contains( icl_float_set, pi ); would be problematic anyway since pi can not be represented precisely. right_open_interval<float> pi_itv = interval_around_pi(); icl::contains( icl_float_set, interval_around_pi() ); // better
Does icl::contains( icl::interval_set< int >(), 0 ); compile, but icl::contains( icl::interval_set< float >(), 0. ); does not for the same reason?
yes. I have mentioned in the docs, that 'continuous_interval' is the only class template that allows to represent a singleton interval that contains only one element, an have provided a small example here: http://www.boost.org/doc/libs/1_46_0/libs/icl/doc/html/boost_icl/interface.h... Regards, Joachim -- Interval Container Library [Boost.Icl] http://www.joachim-faulhaber.de