Re: [boost] [none_t] I/O operators patch

Subject: Re: [boost] [none_t] I/O operators patch
From: Krzysztof Czainski (1czajnik_at_[hidden])
Date: 2011-06-05 20:23:11

2011/6/6 Gregory Crosswhite <gcross_at_[hidden]>

> Hey everyone,
>
> Since my idea to add I/O operators for none_t has been approved by the
> community according to the three-week rule --- which as you all know states
> that any proposals that have received no feedback on the list after three
> weeks are therefore automatically approved by the community ;-) --- I have
> written a patch based on the feedback I have received to implement these
> operators and attached it to this e-mail.  To summarize my earlier e-mail,
> the advantage of having these operators around is that they allow generic
> I/O code to be applied to data of type none_t.
>
> One decision that I made in this patch that I have mixed feelings about is
> that I put the operators in the boost namespace.  The advantages of this
> approach are obvious, but the disadvantage is that this "hides" them from
> the user who might not realize that he or she needs to import operator>> and
> operator<< in order to access them (since importing qualified operators is
> something that is not usually done) but instead conclude they they don't
> exist at all.  Alternatives include putting them in the global namespace and
> putting them in the std namespace.  Any thoughts on this?
>
> Since the window for adding new features to Boost closes tomorrow, and this
> patch is relatively small and should be fairly innocuous, is there a chance
> that this or something like it could be considered for the next release?
>
> Thanks!  :-)
> Greg
>

Hi Greg,

I personally don't see any use for these operators, nor any harm they could
do.

About your namespace concern: wolud these operators be found via ADL, if you
put them into the same namecpace, as none_helper (that is boost::detail)?

Also, did you consider adding these operators to another file (i.e.
none_t_io.hpp), so that users of none_t, who (usually) don't need these
operators, don't get <iosfwd> on the way? Notice, that boost::none is
defined in a separate file too.

Regards
Kris