Re: [boost] Bounded types (or maybe not 'bounded' anymore? ;-)

From: Jeff Garland (jeff_at_[hidden])
Date: 2005-09-25 16:06:06

On Sun, 25 Sep 2005 22:08:32 +0200, Robert Kawulak wrote
> Hi group,
>  
> > Some time ago I've written a set of class templates for 
> > bounded types (types
> > whose variables may hold a value only from within a specified 
> > range).
> 
> Just today I've discovered, that basic_bounded class template is 
> even more flexible than I thought! :-) It may be used for types 
> holding their values not only within a specified range, but 
> virtually any set (or, in other words, values conforming to any 
> criterion). For instance a policy template may be written very 
> easily for even numbers only. When it's used as basic_bounded's 
> policy parameter, the new type will only accept even values:
> 
> -------------------------------------------
> 
> template<typename T>
> struct even_policy; // implementation not included for conciseness
> 
> typedef basic_bounded< even_policy<int> > even_int;
> even_int i;
> 
> i = 2; // OK
> i = 3; // illegal
> i += 2; // OK
> i += 3; // illegal
> i++; // illegal, might even generate a compiler error
> 
> -------------------------------------------
> 
> Therefore I think that this flexibility should be reflected in the 
> name of the basic_bounded template as well as the library in 
> general. Maybe it should be something like 'restricted' meaning that 
> the types may hold only values restricted by some constraint? Or 
> maybe 'constrained'? Could some native english speaker write which 
> he thinks is the most appropriate name?

Restricted is ok, but I like constrained better.  Please see:

http://www.boost.org/doc/html/constrained_value.html
http://www.boost.org/boost/date_time/constrained_value.hpp
http://www.artima.com/weblogs/viewpost.jsp?thread=79470

Jeff