Re: [Boost-bugs] [Boost C++ Libraries] #5375: is_container itself should be MPL boolean instead of type typedef.

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #5375: is_container itself should be MPL boolean instead of type typedef.
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2011-03-27 15:03:00

#5375: is_container itself should be MPL boolean instead of type typedef.
----------------------------------------------------+-----------------------
  Reporter:  Yasutaka ATARASHI <atara-y@…>          |       Owner:  hkaiser
      Type:  Bugs                                   |      Status:  closed 
 Milestone:  To Be Determined                       |   Component:  spirit 
   Version:  Boost 1.46.0                           |    Severity:  Problem
Resolution:  worksforme                             |    Keywords:         
----------------------------------------------------+-----------------------
Changes (by hkaiser):

  * status:  new => closed
  * resolution:  => worksforme

Comment:

 Replying to [comment:3 anonymous]:
 > Replying to [comment:2 hkaiser]:
 > > Sorry I do not understand your problem.
 `boost::spirit::traits::is_container<>` is derived from `mpl::bool_<>`
 (see $BOOST_ROOT/boost/spirit/home/support/contain.hpp). What's wrong with
 that?
 >
 > Sorry for unclarity. Implementation has no problem. The problem point is
 documentation.
 > is_container is provided for customization point. A reader who wants to
 provide is_container can misunderstand providing `type' is enough,
 according to the current documentation because "Expression Semantics" only
 mentions `type'.

 The documentation clearly states that `is_container<C>::type` has to
 evaluate to an MPL boolean constant (see expression semantics here:
 http://www.boost.org/doc/libs/1_46_1/libs/spirit/doc/html/spirit/advanced/customize/is_container.html#spirit.advanced.customize.is_container.expression_semantics).

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/5375#comment:4>
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