From: daniel.kruegler@googlemail.com   
      
   Am 31.08.2012 23:16, schrieb Marco Guazzone:   
     > On Friday, August 31, 2012 12:13:36 AM UTC+2, Daniel Krügler wrote:   
     > [cut]   
     >   
     >>> But, when the container is a map (or similar), what do you use?   
     >>   
     >> It certainly depends what you want to realize. There are clearly   
     >> reasonable use-cases, where the associative container can be   
     >> considered as a sequence of elements. This makes sense, because   
     >> associative containers and unordered containers also satisfy the   
     >> Container requirements.   
     >>   
     >>> Possibile candidates:   
     >>>   
     >>> 1. Two parameters: the first/last iterator pair:   
     >>>        map<...,...> m;   
     >>>        foo(m.begin(), m.end())   
     >>   
     >> Yes, this is IMO a very intuitive one. But you may need to explain   
     >> what foo is going to do, before we speculate on that.   
     >   
     > You're right.   
     > In fact, a possible issue with this signature is when you pass   
     > iterators to multimap. 'foo', to work correctly, should not make   
     > any assumption on the uniqueness of the first element of each pair.   
     >   
     > Maybe, in that case, it would be better to directly pass the   
     > container?   
      
   The reason I was asking about foo is related to that. If foo is a very   
   general operation that can be performed without having a container at   
   hand, it makes very much sense in C++11 (without a proper range   
   concept) to provide an overload accepting a pair of iterators   
   representing a range.   
      
     >>> 2. Four parameters: the first/last iterator pair representing the   
     > [cut]   
     >>   
     >> I do'n see much value of this signature, but I certainly think   
     >> that it would be nice to have a view on std::map that solely   
     >> iterates over its keys or over its values. Java's Map interface   
     >> provides these views and I would say that these two views are   
     >> quite often used.   
     >   
     > Yes I agree. In addition to Java, there're many other languages   
     > that have them (e.g., D, Perl, PHP and Python, just to name a   
     > few). It's a pity that C++11 does not have them, or am I wrong?   
     >   
     > [cut]   
     >   
     >> I would consider as a different approach that accepts a range as   
     >> argument. Certainly this approach is often very useful as well,   
     >> for any container. The very advantage is that the caller has no   
     >> chance to provide a wrong combination of iterator arguments.   
     >   
     > Interesting. I assume you're referring to Boost.Range, are you?   
      
   Yes, for example. I really think that C++ should introduce a range   
   template. Unfortunately it didn't make it into C++11.   
      
   If such a range template exists, it would be much simpler to add two   
   functions associated with the map types that return a range over they   
   key elements or over the mapped value elements.   
      
   HTH & Greetings from Bremen,   
      
   Daniel Krügler   
      
      
      
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