Re: [Boost-users] [bimap] Creating a bimap fom a std::map

Subject: Re: [Boost-users] [bimap] Creating a bimap fom a std::map
From: Lex Wassenberg (lex.wassenberg_at_[hidden])
Date: 2009-11-26 04:55:10

I am not sure wether I understand this whole discussion, but I think
that I do so I would like Edward to consider this:

Suppose you have a std::map<int, int> m with the elements (1,10),
(2,20), (3,20), (4,20), (5,30), and you code:
  Boost::bimap<int,int> bm(m);

Now what??

Regards

Lex

> -----Oorspronkelijk bericht-----
> Van: boost-users-bounces_at_[hidden] [mailto:boost-users-
> bounces_at_[hidden]] Namens Matias Capeletto
> Verzonden: Wednesday, 25 November 2009 23:50
> Aan: boost-users_at_[hidden]
> Onderwerp: Re: [Boost-users] [bimap] Creating a bimap fom a std::map
> 
> On Wed, Nov 25, 2009 at 5:35 PM, Edward Diener
<eldiener_at_[hidden]>
> wrote:
> > Whether I go:
> >
> > bm.left.insert( m.begin(), m.end() );
> >
> > or
> >
> > bm.right.insert( m.begin(), m.end() );
> >
> > ,when both types are the same, is totally irrelevant to further use
of
> the
> > bimap. Is this not correct ?
> 
> No, it is not correct. A bimap is a mapping between two sets of
> elements (named the left set, and the right set) that can be viewed as
> a std map<L,R> or as a std map<R, L>. In this particular example both
> sets hold elements of the same type but which one is the left and
> which one is the right matters. Imagine that you need a mapping
> between names and surnames
> (bimap<tagged<string,name>,tagged<string,surname> >), and you want to
> insert from a std::map<string,string> that maps from surnames to
> names.
> I hope it is more clear now.
> Regards
> Matias
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