[boost] Re: [iterator_facade] postfix ++/--

From: David Abrahams (dave_at_[hidden])
Date: 2004-07-13 12:24:39

David Abrahams <dave_at_[hidden]> writes:

> Doug Gregor <dgregor_at_[hidden]> writes:
>
>> On Jul 13, 2004, at 5:49 AM, David Abrahams wrote:
>>> Synge Todo <wistaria_at_[hidden]> writes:
>>> It appears that the old input iterator requirements require that *r++
>>> returns value_type instead of a proxy.  However, *r++ must be a proxy
>>> if the iterator is writable.  Since there's no way to detect iterator
>>> writability reliably, I'm going to have to make *r++ return value_type
>>> whenever the specified iterator category is strictly
>>> std::input_iterator_tag.
>>>
>>> I'll let everyone know when it's checked in
>>
>> FYI, the operations_test.cpp test of the filesystem lib fails unless
>> the return type of *r++ is value_type (where r is a
>> directory_iterator). The problematic line is, of course:
>>
>> BOOST_TEST( (*dir_itr++).leaf() == "d2" );
>
> Actually, looking at the test, it's just wrong by any measure.
> The only thing it was compatible with was the old broken semantics
> for iterator_facade's postfix increment when it was implementing an
> input iterator.  To be consistent with C++98, it should be
>
>   BOOST_TEST( (*dir_itr++).leaf() == "d1" );
>                                        ^
>
> And to be consistent with the current WP, it should be
>
>   BOOST_TEST(implicit_cast<std::string const&>((*dir_itr++)).leaf() == "d1" );
>                                        
>
> I'll update the test appropriately.

OK, all fixed and checked in.

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