Re: [boost] [multi_index] composite keys: request for advice

From: Brian McNamara (lorgon_at_[hidden])
Date: 2004-04-24 23:05:24

On Sun, Apr 25, 2004 at 03:54:31AM +0200, JOAQUIN LOPEZ MU?Z wrote:
> > that if you call these two object "k" and "t" (key and tuple), 
> > then you should have
> >   k < t      false
> >   t < k      false
> >   t == k     does not compile
> > That's just my quick hunch based on what I've quoted above; I haven't
> > considered what consequences it has for the library, but that's my
> > intuitive notion of how tuples as "partial keys" ought to work.
> 
> I guess I agree with you, but I wanted to bring this
> in to the list to gather some opinions. Following your
> approach, what should we do with
> 
>   k <= t
>   t <= k
> 
> The options are:
> 
>  a. they hold true
>  b. they do not compile
> 
> I don't have any strong argument in favor of any option.

If there are other std:: or boost:: types which model the
StrictWeakOrdering concept (without having total orders), I would see
what they do and follow their lead.

If not, I would make the "<=" operators not compile, since
   k <= t
can always be rewritten by clients as
   !(t < k)
and the narrower interface reduces the likelihood of someone mistakenly
getting the impression that there's a total ordering here (IMO).

-- 
-Brian McNamara (lorgon_at_[hidden])