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From Steve Downey <steve.dow...@netfolio.com>
Subject Re: [lang] Ideas for Lang
Date Mon, 14 Oct 2002 19:40:46 GMT
On Monday 14 October 2002 02:26 pm, bob mcwhirter wrote:
> > > I was hoping there might be a good Lisp fanatic or something with some
> > > reasons for why a Pair object would be very useful. I seem to recall
> > > reading someone's blog opining for a Pair class.
> >
> > Well, you could certainly do lists the LISP way with a Pair class. One
> > element is the CAR and the other is the CDR. Then you could build the
> > other list operations on top of it quite simply. That's not to say this
> > is a good idea, but you *could*. ;-)
>
> Also, for some hysterical perspective, I believe the STL returned an
> Iterator<Pair<KEY,VALUE> > from Map::iterator().
>

On the other hand, Java Collections explicitly rejected the notion that a Map 
is a collection of pairs. It's one of the reasons that List and Map are 
irreconcilable.

> > Of course, this begs the question of what *do* you call the elements of a
> > generic Pair class, to avoid implying any semantic. I guess you can't
> > really go far beyond 'obj1' and 'obj2'.
>
> Yes, I believe the STL's Pair had getFirst() and getSecond().
>

I think that's about all you can say about them. It's not like this a deep 
class. But if you've got them in a few places, they might as well be the 
same.

If there's anyplace a Pair would come in handy in commons, I'd be for it, 
otherwise, I don't see the general use.

> We're not breaking new ground here...
>
> 	-bob


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