Hi!<div>Is someone responsible for iterator_facade? Would be great if I&#39;d be able to clarify this with one of the authors...</div><div><br></div><div>Many thanks,</div><div>Ovanes<br><br><div class="gmail_quote">On Wed, Aug 17, 2011 at 2:58 PM, Ovanes Markarian <span dir="ltr">&lt;<a href="mailto:om_boost@keywallet.com">om_boost@keywallet.com</a>&gt;</span> wrote:<br>

<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">Hello *!<div><br></div><div>I defined a custom bidi-iterator and assumed it was going to support std::advance(iterator, Difference n), where n can be negative for random access and bidirectional iterators.</div>

<div><br></div>
<div>The definition of my iterator&#39;s facade base looks like:</div><div><div>struct my_iter </div><div>  : boost::iterator_facade</div><div>      &lt; my_iter</div><div>      , const byte</div><div>      , boost::bidirectional_traversal_tag </div>


<div>      , const byte</div><div>      &gt;</div></div><div>{</div><div><br></div><div>// some impl stuff follows...</div><div>};</div><div><br></div><div><br></div><div>My tests show that calling:</div><div>advance(instance_of_my_iter, N) works fine (increment implementation is called)</div>


<div><br></div><div>advance(instance_of_my_iter, -N) does not work, because increment (instead of decrement) is called as well</div><div><br></div><div>While reading through the docs for iterator facade at <a href="http://www.boost.org/doc/libs/1_46_0/libs/iterator/doc/iterator_facade.html" target="_blank">http://www.boost.org/doc/libs/1_46_0/libs/iterator/doc/iterator_facade.html</a> I found the section <span style="font-family:sans-serif;font-size:13px;font-weight:bold;line-height:15px;background-color:rgb(255, 255, 255)"><tt><span style="white-space:pre-wrap">iterator_facade</span></tt> Core Operations.</span></div>


<div><br></div><div>For the advance implementation is stated there that it is only gets called for Random Access Iterators. C++ Standard clearly defines that N-Parameter to std::advance can be negative to random access and bidi iterators. Implementing void advance member in my_iter still results in the call to increment member. Can someone give me any suggestions or is it a bug in the iterator lib?</div>


<div><br></div><div>My compiler is gcc 4.3 under Debian Linux with Kernal 2.6.26. and Boost 1.42.</div><div><br></div><div><br></div><div>With Kind Regards,</div><div>Ovanes</div><font color="#888888"><div><br></div>
</font></blockquote></div><br></div>