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Groups > comp.lang.c++ > #12039

Returning map from map of maps without any copy

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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

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Thread

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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