Re: [Boost-bugs] [Boost C++ Libraries] #3446: [boost] [fusion] transform does not return a mutable view

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #3446: [boost] [fusion] transform does not return a mutable view
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2009-09-14 06:45:27

#3446: [boost] [fusion] transform does not return a mutable view
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 Reporter:  jhellrung@…         |       Owner:  djowel      
     Type:  Feature Requests    |      Status:  new         
Milestone:  Boost 1.41.0        |   Component:  fusion      
  Version:  Boost 1.40.0        |    Severity:  Optimization
 Keywords:                      |  
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Comment(by djowel):

 > First, I wasn't aware that assignment of a Boost.Fusion sequence to,
 e.g., a boost::array would work? I admit I've never tried it...

 Ah indeed it won't. boost::array is not a fusion container. So you have a
 good use case for copy indeed. I suggest you polish it, provide docs, and
 I'd gladly add that to the library.

 Now, back to what you want. It seems that you don't need in-place mutation
 at all!

     copy(transform(src, project()), dest);

 where project returns src[i].member_var for each member. This is as fast
 as you expect it to be since transform is lazily evaluated.

 Thoughts?

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/3446#comment:5>
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