[Boost-bugs] [Boost C++ Libraries] #1262: [Boost.Iterators] Reasoning for boost::pointee<> not supporting back_insert_iterator?

Subject: [Boost-bugs] [Boost C++ Libraries] #1262: [Boost.Iterators] Reasoning for boost::pointee<> not supporting back_insert_iterator?
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2007-09-13 19:31:18

#1262: [Boost.Iterators] Reasoning for boost::pointee<> not supporting
back_insert_iterator?
-------------------------------------------------------+--------------------
 Reporter:  Richard Hazlewood <richard_at_hazlewoods.eu>  |       Owner:  dave          
     Type:  Support Requests                           |      Status:  new           
Milestone:  To Be Determined                           |   Component:  iterator      
  Version:  Boost 1.34.1                               |    Severity:  Not Applicable
 Keywords:  pointee iterator back_insert_iterator      |  
-------------------------------------------------------+--------------------
 The C++ Standard specifies that ''std::back_insert_iterator'' does not
 pass the ''value_type'' down to the base output-iterator class.  This
 means (by default) that the ''value_type'' is typed to ''void'' and thus
 unsuitable for ''boost::pointee'' to determine the value type.

 E.g.:
 {{{
 typedef std::vector<int> Ints;
 typedef std::back_insert_iterator<Ints> Iter;
 typedef boost::pointee<Iter>::type IntType; // Errors
 }}}

 The following specialization can be used to support
 ''back_insert_iterator'':
 {{{
 namespace boost
 {
     template <class T>
     struct pointee<std::back_insert_iterator<T> >
     {
         typedef typename T::value_type type;
     };
 }
 }}}

 Is there a particular reasoning why this is not available in the library?

 Note: this also applies to ''std::front_insert_iterator''.

-- 
Ticket URL: <http://svn.boost.org/trac/boost/ticket/1262>
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