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Re: Returning map from map of maps without any copy

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On 12/3/2011 12:38 PM, ittium wrote:
> Group,
> I have a class that contains (STL) map of maps. This Class has a getMap
> function that return one map out of the map of maps. I need to avoid
> copies while extracting the map. There are two approaches
> 1. I pass a "map" reference in getMap function, the getMap method
> extract appropriate map and put it in the passed map reference. It seems
> copy will be made while doing
> map=Extracted Map; //map is reference parameter in getMap function
>
> 2. Second option is to return a reference from the getMap function
> (please ignore dangling pointer issue since this class is likely to live
> forever). My doubt is
> - Can I return a iterator->second as reference
> - If I can return it, how can caller save it (without making a copy).
>
> Please note that maps to be returned are big and copying them is going
> to be a big overhead.'
>
> Is there a better solution to handle this.
> thanks
> Ittium
>

Thanks everyone for the explanation. I will return the appropriate map 
by reference and save it in reference. This will avoid all the copies 
and solve the issue.

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Returning map from map of maps without any copy ittium <ittium@gmail.com> - 2011-12-03 12:38 +0530
  Re: Returning map from map of maps without any copy Ian Collins <ian-news@hotmail.com> - 2011-12-03 20:36 +1300
  Re: Returning map from map of maps without any copy Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-12-03 09:27 +0000
  Re: Returning map from map of maps without any copy Goran <goran.pusic@gmail.com> - 2011-12-03 02:05 -0800
  Re: Returning map from map of maps without any copy ittium <ittium@gmail.com> - 2011-12-08 11:29 +0530

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