[Boost-users] Re: Iterators and maps [was Re: Where should STL suggestionsgo?]

From: David Abrahams (dave_at_[hidden])
Date: 2004-12-13 13:59:50

Ben Hutchings wrote:
> Jim Lear wrote:
>> The map iterators are really what tripped me up as an STL newbie.  One 
>> must understand the iterators are implemented as pairs for maps, and 
>> pointers for vectors and other things.  By providing an "T 
>> operator[](iterator)" function for random access and associative 
>> containers (and for sequences maybe), one could achieve a consistant 
>> interface.
> 
> Container-independent code is an impossible and pointless goal.  maps 
> have different semantics from other containers.  You may want to iterate 
> over just the mapped values, but other people may want to iterate over 
> the keys, or over the pairs (and indeed, so may you, in other part of 
> your program).  Who's to say which of these is right?  What you can do 
> is to write iterator-independent code, then use an iterator adapter to 
> convert the iterators over pairs into iterators over the mapped values:

Have you seen http://www.zib.de/weiser/vtl/ and
http://www.boost.org/libs/range/index.html?

-- 
Dave Abrahams
Boost Consulting
http://www.boost-consulting.com