[Boost-users] Re: HowTo Iterator Facade

From: David Abrahams (dave_at_[hidden])
Date: 2004-12-04 20:29:23

Peter Dimov wrote:
> David Abrahams wrote:
> 
>> Duane Murphy wrote:
>>
>>> I am implementing an iterator via iterator facade. The container
>>> that the iterator is being used with can only return dereferenced
>>> values by value (not by reference).
>>>
>>> If I implement the dereference() function (for facade) by returning a
>>> value (instead of reference) then it appears that the iterator works
>>> properly.
>>> The most important operation that does _not_ work is that the
>>> iterator cannot be used with bind(). (bind cannot be used with non-const
>>> return types.) 
>>
>>
>> Sorry, I can't imagine what you mean.  Of course bind works with
>> non-const return types: [...]
> 
> 
> Probably the following:
> 
>    std::for_each( first, last, boost::bind( f, _1 ) );
> 
> When *first returns a non-const rvalue, bind can't take it.

I guess the answer is to make the reference type const, then.

-- 
Dave Abrahams
Boost Consulting
http://www.boost-consulting.com