If you like. Either we add setComparator/getComparator, or we remove the
undesirable no-op constructor. If it were me, I'd just do the later, but
I'm not in the "make every class a bean" camp.
----- Original Message -----
From: "Henri Yandell" <[EMAIL PROTECTED]>
To: "Jakarta Commons Developers List" <[EMAIL PROTECTED]>;
"Morgan Delagrange" <[EMAIL PROTECTED]>
Sent: Tuesday, March 19, 2002 2:08 PM
Subject: Re: [collections] ReverseComparator
> The only reason I'd normally expect to have an empty constructor would be
> for reflection. To that end, should it have a setComparator/getComparator
> methods?
>
> Hen
>
> On Tue, 19 Mar 2002, Morgan Delagrange wrote:
>
> > Do we need an empty constructor? If it does not produce desirable
> > behaviour, why not can it?
> >
> > ----- Original Message -----
> > From: "Henri Yandell" <[EMAIL PROTECTED]>
> > To: "Jakarta Commons Developers List" <[EMAIL PROTECTED]>
> > Sent: Tuesday, March 19, 2002 11:11 AM
> > Subject: Re: [collections] ReverseComparator
> >
> >
> > >
> > > Functionality wise, I feel that Michael's proposed change is a
negative
> > > move. However he is absolutely right in all of his points. The
current -1
> > > does break the Comparator contract, the -1* is unnecessary coding,
making
> > > the constructor take ComparableComparator is then no different from
> > > reverseOrder, and the name then does make more sense as
InverseComparator.
> > >
> > > It's like a stack of dominoes :) Each point seems not necessarily true
> > > until you realise each one leads to the next. So I'm:
> > >
> > > +1 on removing the -1*.
> > > +1 on killing the current empty constructor.
> > > +0 on using ComparableComparator which simulates reverseOrder
> > functionality.
> > > It feels bad to replicate this, but we need an empty constructor.
> > > +0 on the name of the class. It does behave more as an
InverseComparator
> > > from a mathematical point of view (which I share), but Reverse does
> > > seem more readable.
> > >
> > > Hen
> > >
> > >
> > > On Tue, 19 Mar 2002, Morgan Delagrange wrote:
> > >
> > > > Michael suggested that the no-op constructor essentially behave like
> > this:
> > > >
> > > > ReverseComparator() {
> > > > this(ComparableComparator.getInstance());
> > > > }
> > > >
> > > > What do you think, Hen? Do you think that is preferable, or do you
> > prefer
> > > > your initial behaviour (reversing the List).
> > > >
> > > >
> > > > ----- Original Message -----
> > > > From: "Henri Yandell" <[EMAIL PROTECTED]>
> > > > To: "Jakarta Commons Developers List"
<[EMAIL PROTECTED]>
> > > > Sent: Tuesday, March 19, 2002 7:50 AM
> > > > Subject: Re: [collections] ReverseComparator
> > > >
> > > >
> > > > >
> > > > > I'm happy with the name Inverse as it is more what the comparator
> > does.
> > > > > Reverse makes it easier to see how it can be used for one case,
but
> > will
> > > > > hide other meanings.
> > > > >
> > > > > Why does this exist over Collections.reverseOrder? Because the Sun
> > version
> > > > > is limited. Why can I only reverse Comparables? Really there
should be
> > a
> > > > > Collections.reverseOrder(Comparator) as well.
> > > > >
> > > > > Hen
> > > > >
> > > > > > I agree that reverse is common terminology when sorting, but I
> > disagree
> > > > > > that sorting is intrinsicly what a comparator does. While
sorting is
> > > > > > probably the most common use-case for comparators, the
comparator
> > itself
> > > > > > does not do any sorting. It compares objects and returns a
> > negative,
> > > > zero
> > > > > > value, or positive result. It doesn't rearrange, reverse,
order, or
> > > > > > "sort". It just compares two objects. This particular
comparator
> > > > > > "inverses" the result of the compare to be a positive, zero
value,
> > or
> > > > > > negative result (respectively). I use "inverse" here in its
> > > > mathematical
> > > > > > sense of inverting the result, since that's all this comparator
is
> > > > doing.
> > > > > >
> > > > > > I'm not going to argue this anymore though. I've changed my
> > position --
> > > > > > why is this class even included in commons when the JDK provides
a
> > > > > > reverse/inverse comparator already? @see
Collections.reverseOrder()
> > > > > >
> > > > > > regards,
> > > > > > michael
> > > > > >
> > > > > > > "Michael A. Smith" wrote:
> > > > > > > >[snip]
> > > > > > > > Additionally, I think that "InverseComparator" is a more
> > appropriate
> > > > name,
> > > > > > > > as "inverse" has a more direct meaning (to me at least).
> > Inverse
> > > > has the
> > > > > > > > mathematical meaning of the opposite sign which is exactly
what
> > this
> > > > > > > > comparator does. Reverse, on the other hand, implies
switching
> > the
> > > > order
> > > > > > > > of something, the comparator isn't really switching the
order
> > > > (although a
> > > > > > > > collection using the comparator may be "reversed" if it uses
the
> > > > "inverse"
> > > > > > > > comparator).
> > > > > > > >
> > > > > > > > Thoughts?
> > > > > > > >[snip]
> > > > > > >
> > > > > > >
> > > > > >
> > > > > >
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