Re: [boost] [reference_wrapper] Overloading operator() inreference_wrapper

Subject: Re: [boost] [reference_wrapper] Overloading operator() inreference_wrapper
From: Nathan Crookston (nathan.crookston_at_[hidden])
Date: 2013-05-02 11:10:41

Hi all,

Peter Dimov wrote:

> Kazutoshi Satoda wrote:
>
>> The standard version has 4 member typedef which are conditionally
>> defined: result_type, argument_type, first_argument_type,
>> second_argument_type. If "to update boost::ref to match the standard
>> version" includes addition of these members, it requires the argument
>> type complete to determine the condition to (or not to) define these
>> typedef. If you decide not to define these typedef based on the
>> incompleteness, it will likely cause ODR violation.
>>
>
> Interesting. I've always considered these typedefs redundant, but this is
> the first time I see them as actively harmful.
>

Yes, this is good to know.  I wondered why the standard bothered to specify
that in our new, decltype-enabled world.  I'll update the ticket to
reference this discussion.  Happily, just having an operator() overload
shouldn't require completeness.

Thanks,
Nate