Re: [Boost-bugs] [Boost C++ Libraries] #3768: Incomplete documentation for type_traits::extent and type_traits::rank

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #3768: Incomplete documentation for type_traits::extent and type_traits::rank
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2009-12-16 01:36:59

#3768: Incomplete documentation for type_traits::extent and type_traits::rank
------------------------------------------------+---------------------------
 Reporter:  Edward Diener <eld@…>               |       Owner:  johnmaddock
     Type:  Bugs                                |      Status:  new        
Milestone:  Boost 1.42.0                        |   Component:  type_traits
  Version:  Boost 1.41.0                        |    Severity:  Cosmetic   
 Keywords:  extent rank                         |  
------------------------------------------------+---------------------------

Comment(by Edward Diener <eld@…>):

 Replying to [comment:1 anonymous]:
 > So what would you suggest?
 >
 > >Inherits: Class template extent inherits from
 integral_constant<std::size_t, >EXTENT(T,N)>, where EXTENT(T,N) is the
 number of elements in the N'th array dimention >of type T.
 > >If T is not an array type, or if N > rank<T>::value, or if the N'th
 array bound is >incomplete, then EXTENT(T,N) is zero."
 > >
 > >This does not explain what this type_traits is about.
 >
 > Really?  Concise maybe, but how does "where EXTENT(T,N) is the number of
 elements in the N'th array dimention of type T" not precisely describe the
 traits behaviour?
 >
 > John.

 I know it is said that:

 'EXTENT(T,N) is the number of elements in the N'th array dimention of type
 T'

 but I am not really sure what this means ( forget the misspelling of
 'dimention', I know it is really 'dimension' ). Does this mean that T must
 be a C-style array ? If T must be a C-style array, does this mean that if
 T is, for example 'int [4][7]' that EXTENT(T,1) is 7 ? Or is there
 something else in both these assumptions.

 Perhaps the problem is mine and I am looking into the words 'array' and
 'dimension' for something that is not there.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/3768#comment:2>
Boost C++ Libraries <http://www.boost.org/>
Boost provides free peer-reviewed portable C++ source libraries.