Re: [Boost-users] Container/Algorithm question

From: Elisha Berns (e.berns_at_[hidden])
Date: 2005-07-19 20:59:41

Joaquin,

Well, sorry for having bothered you so much with what turned out to be
such a knuckleheaded question!  It was option II, so std:set worked
fine.

Thanks again,

Elisha

> -----Original Message-----
> From: boost-users-bounces_at_[hidden] [mailto:boost-users-
> bounces_at_[hidden]] On Behalf Of Joaquín Mª López Muñoz
> Sent: Monday, July 18, 2005 8:03 AM
> To: boost-users_at_[hidden]
> Subject: Re: [Boost-users] Container/Algorithm question
> 
> 
> 
> Elisha Berns ha escrito:
> 
> > Hi Joaquin,
> >
> > You're right, the code is simple, what could possible wrong, it must
be
> > a communication error on my part regarding what I need it to do!  So
> > I'll try to explain what happens and why I need something else to
> > happen!
> >
> > The insertion errors show up when you run it in a simple nested loop
> > (see test.cpp).  After the first iteration of the outer loop it
fails,
> > because the values for pair.second (created by the inner loop)
already
> > exist in the indices.  But every pair created by that simple nested
loop
> > needs to be valid, it should only fail when a duplicate of the same
> > exact pair is inserted.  The requirement is that every pair in the
range
> > (0..N, 0..M) be valid.  So that means there are N*M valid pairs
(0..N,
> > 0) (0..N, 1) (0..N, 2) etc.  But the code you graciously supplied me
> > doesn't do that!
> >
> 
> Hello Elisha,
> 
> If I understand you now, you need nothing but a std::set of pairs,
which
> by default are ordered lexicographically. Please see the attached
snippet,
> is this what you're after?
> 
> My Boost.MultiIndex-based proposal implemented a different
> containment policy: an element is allowed into the container if
> 
> (Containment policy I)
>   a) there is no other element with the same first value
>   OR
>   b) there is no other (possibly different) element with the same
second
>   value.
> 
> while what (I think) you want is
> 
> (Containment policy II)
>  a) there is no other element with the same first value AND second
value.
> 
> Yet a third alternative is
> 
> (Containment policy III)
>   a) there is no other element with the same first value
>   AND
>   b) there is no other (possibly different) element with the same
second
>   value.
> 
> Are you after (I), (II) or (III)? If (II), std::set will suffice. (I)
can
> be
> implemented with Boost.MultiIndex, as discussed previously, while
(III)
> can
> also be implemented with Boost.MultiIndex.
> 
> Joaquín M López Muñoz
> Telefónica, Investigación y Desarrollo