Re: [Boost-bugs] [Boost C++ Libraries] #8606: Impossible to convert 0-size tuple to (empty) sequence any more

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #8606: Impossible to convert 0-size tuple to (empty) sequence any more
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2015-05-17 14:04:13

#8606: Impossible to convert 0-size tuple to (empty) sequence any more
-------------------------------+---------------------------
  Reporter:  vz-boost@…        |      Owner:  no-maintainer
      Type:  Bugs              |     Status:  closed
 Milestone:  To Be Determined  |  Component:  preprocessor
   Version:  Boost 1.53.0      |   Severity:  Regression
Resolution:  fixed             |   Keywords:
-------------------------------+---------------------------

Comment (by eldiener):

 It is not useful to have a tuple of 0 size and not be able to distinguish
 between '()' as a tuple of size 0 or a tuple of size 1 with the single
 element as empty. Since emptiness is perfectly allowable in the
 preprocessor, and since '(x,)' is clearly a tuple whose size is 2 with the
 second element being empty, it would always be wrong to make a special
 case for '()' and declare that this is tuple of size 0. Furthermore
 treating '()' as a apecial case would make it impossible to have a tuple
 of size 1 whose single element is empty.

 The VC++ preprocessor is a C++ non-standard conforming preprocessor and it
 is only with heroic effort that Paul Mensonides was able to get VC++ to
 handle Boost PP processing as much as it does ( there are numerous
 workarounds in Boost PP code just to handle VC++ ). The gcc preprocessor
 is vastly closer to the C++ standard.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/8606#comment:5>
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