Re: [Boost-bugs] [Boost C++ Libraries] #7730: Generic specializations of is_nullary for custom terminals are not possible

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #7730: Generic specializations of is_nullary for custom terminals are not possible
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2014-02-04 00:10:58

#7730: Generic specializations of is_nullary for custom terminals are not possible
-------------------------------+---------------------
  Reporter:  andysem           |      Owner:  theller
      Type:  Bugs              |     Status:  new
 Milestone:  To Be Determined  |  Component:  phoenix
   Version:  Boost 1.52.0      |   Severity:  Problem
Resolution:                    |   Keywords:
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Comment (by John Fletcher <J.P.Fletcher@…>):

 Replying to [ticket:7730 andysem]:
 >
 > The is_nullary trait has a second template parameter which is intended
 to be used exactly for this purpose. A nested tag void typedef can be used
 to match the trait for a set of types. I could create the following
 specialization:
 >
 > {{{
 > template <typename T>
 > struct is_nullary<custom_terminal<T>, typename T::_is_my_terminal >
 >     : mpl::false_
 > {};
 > }}}
 >

 Note: I have not implemented this part of your example because as I read
 it this part will go into your client code. Is that correct?

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/7730#comment:2>
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