Re: [Boost-bugs] [Boost C++ Libraries] #5473: [Foreach] non-const rvalue collections are treated as const collections

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #5473: [Foreach] non-const rvalue collections are treated as const collections
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2012-11-05 13:03:58

#5473: [Foreach] non-const rvalue collections are treated as const collections
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  Reporter:  mimomorin@…              |       Owner:  eric_niebler
      Type:  Patches                  |      Status:  closed      
 Milestone:  To Be Determined         |   Component:  foreach     
   Version:  Boost Development Trunk  |    Severity:  Problem     
Resolution:  wontfix                  |    Keywords:              
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Comment (by bernd.loerwald@…):

 It actually is not non-sense.

 Given a class being a facade container to an actual container, one might
 construct the facade container on the fly:
       values_type values() const { return values_type (*this); }
 and use it in a manipulating way:
         BOOST_FOREACH (elem_type& elem, values())
 with values_type having non-const iterators, that iterate over the actual
 container (which is referenced in values_type).

 This will fail, as values() returns an rvalue, thus only const iteration
 is possible. It would be perfectly valid to modify the elements iterated
 over with the facade.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/5473#comment:5>
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