[Boost-bugs] [Boost C++ Libraries] #6925: BooleanMetafunction

Subject: [Boost-bugs] [Boost C++ Libraries] #6925: BooleanMetafunction
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2012-05-21 16:56:39

#6925: BooleanMetafunction
------------------------------+---------------------------------------------
 Reporter:  ramey             |       Owner:  agurtovoy
     Type:  Bugs              |      Status:  new      
Milestone:  To Be Determined  |   Component:  mpl      
  Version:  Boost 1.49.0      |    Severity:  Problem  
 Keywords:                    |  
------------------------------+---------------------------------------------
 mpl defined the metafunctions max<N1, N2> as:

 N1, N2 any type. with semantics equivalent to:

 typedef if_< less<x,y>,y,x >::type r;

 BUT less<x,y> requires that x & y be a NumericalMetafunction wity x, y
 modeling IntegralConstant.

 So, I believe that N1 and N2 should also be required to model
 IntegralConstant.

 In addition, it makes sense the max (and min) model the concept of
 NumericalMetafunction with value type bool.

 Actually, there should be a concept BooleanMetafunction as short hand for
 NumericalMetafunction.

 I came across this problem when I removed the ::type from min<x, y> and
 got a compile error.  This should work as plus, ... etc do.

 Robert Ramey

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/6925>
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