[Boost-bugs] [Boost C++ Libraries] #3982: mpl::at documentation out of sync with code

Subject: [Boost-bugs] [Boost C++ Libraries] #3982: mpl::at documentation out of sync with code
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2010-03-06 11:03:41

#3982: mpl::at documentation out of sync with code
---------------------------------------------+------------------------------
 Reporter:  manfred.doudar@…                 |       Owner:  agurtovoy    
     Type:  Bugs                             |      Status:  new          
Milestone:  Boost 1.43.0                     |   Component:  Documentation
  Version:  Boost 1.42.0                     |    Severity:  Problem      
 Keywords:  mpl::at default                  |  
---------------------------------------------+------------------------------
 Documentation of mpl::at indicates that it can take either 2 or 3 template
 parameters, but in fact only takes just 2.  The documentation indicates a
 third template parameter to forward a default if lookup fails to find a
 match.  This option does not exist.

 Code or Documentation should be amended.  If there will be no 3 template
 parameter option, the following would be nice to have in the
 documentation, as how to achieve a default when no match is found:


 typename boost::mpl::eval_if<
     typename boost::mpl::has_key< Map, Key >::type
   , boost::mpl::at< Map, Key >
   , boost::mpl::identity< Default >
   >::type

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/3982>
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