Re: [Boost-bugs] [Boost C++ Libraries] #8024: Unable to create const_iterator for coroutine

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #8024: Unable to create const_iterator for coroutine
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2013-02-18 05:55:31

#8024: Unable to create const_iterator for coroutine
-------------------------------+--------------------------------------------
  Reporter:  nathanridge       |       Owner:  olli     
      Type:  Bugs              |      Status:  reopened 
 Milestone:  To Be Determined  |   Component:  coroutine
   Version:  Boost 1.53.0      |    Severity:  Problem  
Resolution:                    |    Keywords:           
-------------------------------+--------------------------------------------
Changes (by nathanridge):

  * status:  closed => reopened
  * resolution:  fixed =>

Comment:

 What I'm really trying to get to work is code like the following:

 {{{
 #include <iostream>
 #include <boost/coroutine/coroutine.hpp>

 typedef boost::coroutines::coroutine<int()> coro_t;

 void foo(coro_t::caller_type& caller)
 {
     caller(0);
     caller(1);
     caller(2);
 }

 coro_t f()
 {
     return coro_t(&foo);
 }

 template <typename Range>
 void print_range(const Range& range)
 {
     for (auto element : range)
         std::cout << element;
 }

 int main()
 {
     print_range(f());
 }
 }}}

 The C++11 range-based for loop requires either that the range type have a
 member function named 'begin', or that there exist a non-member function
 named 'begin' that is found by argument-dependent lookup (i.e. in the same
 namespace as the range type). In either case, the 'begin' function should
 have a const version that returns a const iterator.

 What that translates to for coroutines is that either coroutine needs to
 have a member function with the signature "begin() const" or there needs
 to be a non-member function named "begin" in "boost::coroutines" that
 takes a "const coroutine&" parameter. (And of course the same for 'end').

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/8024#comment:2>
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