Re: [Boost-bugs] [Boost C++ Libraries] #11399: Boost geometry models don't support stateful allocator.

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #11399: Boost geometry models don't support stateful allocator.
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2015-07-15 14:48:04

#11399: Boost geometry models don't support stateful allocator.
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  Reporter:  bmccart@…         |      Owner:  barendgehrels
      Type:  Feature Requests  |     Status:  new
 Milestone:  To Be Determined  |  Component:  geometry
   Version:  Boost 1.57.0      |   Severity:  Problem
Resolution:                    |   Keywords:  geometry model allocator
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Comment (by awulkiew):

 Indeed, you're right that modern allocator support is missing.

 Unfortunately when the models were implemented in the past some design
 decisions were made, i.e. the allocators are passed as template template
 parameters. If we want to be backward compatibile we must leave it as it
 is. So even if it was allowed to pass stateful allocators objects into the
 constructor the user would be able to use only the allocators taking one
 type parameter. I'm not sure if that'd be useful in general. Would it meet
 your needs?

 If we wanted to support modern allocators we would have to reimplement the
 existing models which would be a breaking change. Maybe this wouldn't be
 that bad because I guess the majority of the users doesn't specify the
 internal containers or allocators at all. Or we could implement additional
 models existing aside from the ones we have now or enable ones or the
 others with a macro definition. None of these solutions is perfect.

 Last but not least, Boost.Geometry is generic. The user can implement his
 own geometry types with ctors taking allocators or whatever he likes and
 adapt these types to Boost.Geometry concepts. So I'm not sure if this
 change is needed, though indeed the models could be modernized.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/11399#comment:1>
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