Re: [Boost-bugs] [Boost C++ Libraries] #10811: Add operators !=, <=, >, >=

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #10811: Add operators !=, <=, >, >=
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2014-12-04 10:59:36

#10811: Add operators !=, <=, >, >=
-------------------------------+-----------------------
  Reporter:  viboes            |      Owner:  apolukhin
      Type:  Feature Requests  |     Status:  assigned
 Milestone:  Boost 1.58.0      |  Component:  variant
   Version:  Boost 1.57.0      |   Severity:  Problem
Resolution:                    |   Keywords:
-------------------------------+-----------------------

Comment (by apolukhin):

 Replying to [comment:3 viboes]:
 > Thanks even if I expected that operator>= be defined in terms of
 operator>= :(

 Current approach reduces binary size. It also follows the Standard Library
 approach (for example `std::vector` implement comparisons in the same way)
 to reduce requirements for ValueTypes.
 [[BR]]
 [[BR]]

 > I find weird making private these kind of overloads.
 >
 >
 > {{{
 >  inline bool operator>=(const variant& rhs) const
 >  {
 >  return !(*this < rhs);
 >  }
 > }}}
 >
 > Does it means that
 >
 >
 > {{{
 > variant< int, string> v = 1;
 > auto x = 1 < v;
 > }}}
 >
 > would compile and
 >
 > {{{
 > variant< int, string> v = 1;
 > auto x = v < 1;
 > }}}
 >
 >
 > wouldn't?

 Both cases won't compile. I was following the existing schema and
 implemented those operators in the same way as `operator==` and
 `operator<` were implemented.

 Though it could be useful to have comparison operators with types that are
 held in variant, just like in your example: `(1 < v || v < 1)`. To do it
 in an effective way some metaprograming pretty close to one required by
 #547 must be done. Created a separate ticket #10845 for this feature.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/10811#comment:5>
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