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From Gary Gregory <garydgreg...@gmail.com>
Subject Re: [lang] ImmutablePair is final
Date Wed, 23 Oct 2013 00:25:57 GMT
On Tue, Oct 22, 2013 at 4:53 PM, Duncan Jones <djones@cantab.net> wrote:

> On 22 October 2013 21:07, Gary Gregory <garydgregory@gmail.com> wrote:
> > On Tue, Oct 22, 2013 at 3:59 PM, Matt Benson <gudnabrsam@gmail.com>
> wrote:
> >
> >> So what is having a non-generic runtime class accomplishing for you?
> >>
> >
> > The subclass "is a kind of" pair AND it is domain typed to my app.
> >
> > Gary
>
> Sebb is correct - composition would work well here. You can still
> defer to the equals/hashcode from the underlying ImmutablePair as you
> appear to store no other state within the class.
>

I could do it that way and end up with a hierarchy likeL

- Lang final ImmutablePair<K,V>
- My ImmutablePairProxy<K, V> wraps an ImmutablePair<K,V>
- My ImmutablePairProxyClass extends ImmutablePairProxy<Foo, Bar>
- My ImmutablePairProxyClass extends ImmutablePairProxy<Zing, Bat>

It's doable but it feels more spaghetti like than subclassing ImmutablePair.

Gary



> Duncan
>
>
> >
> >
> >>
> >> Matt
> >>
> >>
> >> On Tue, Oct 22, 2013 at 2:29 PM, Gary Gregory <garydgregory@gmail.com
> >> >wrote:
> >>
> >> >
> >> >
> >> >
> >> > Sent via the Samsung Galaxy NoteĀ® 3, an AT&T 4G LTE smartphone
> >> >
> >> > -------- Original message --------
> >> > From: sebb
> >> > Date:10/22/2013 13:37 (GMT-05:00)
> >> > To: Commons Developers List
> >> > Subject: Re: [lang] ImmutablePair is final
> >> >
> >> > On 22 October 2013 18:33, Gary Gregory <garydgregory@gmail.com>
> wrote:
> >> > > On Tue, Oct 22, 2013 at 1:22 PM, Paul Benedict <
> pbenedict@apache.org>
> >> > wrote:
> >> > >
> >> > >> If you can subclass, the class will likely be mutable somehow
> >> (accessing
> >> > >> protected or package-private data?) -- even introducing new
> variables
> >> > >> exclusive to the subclass. The "final" keyword is used well here.
> >> > >>
> >> > >
> >> > > Here is my use case for which I've cloned ImmutablePair into my own
> >> > package
> >> > > (yuck):
> >> >
> >> > Composition (rather than extension) would work better here surely?
> >> >
> >> > Surely indeed Shirley ;) (Airplane!)
> >> >
> >> > Right now I am getting hashCode and equals for free with the subclass
> >> > hack.
> >> >
> >> > Gary
> >> >
> >> >
> >> > > public final class ImmutableFooImmutableBarPair extends
> >> > > ImmutablePair<ImmutableFoo, ImmutableBar> {
> >> > >
> >> > >     private static final long serialVersionUID = 123L;
> >> > >
> >> > >     public ImmutableFooImmutableBarPair (final ImmutableFoo foo,
> final
> >> > > ImmutableBar bar) {
> >> > >         super(Validate.notNull(nameMatch),
> Validate.notNull(article));
> >> > >     }
> >> > >
> >> > >     public ImmutableFoo getImmutableFoo() {
> >> > >         return this.getValue();
> >> > >     }
> >> > >
> >> > >     public ImmutableBar getImmutableBar() {
> >> > >         return this.getKey();
> >> > >     }
> >> > > ...
> >> > > ImmutableFooImmutableBarPair pair = new
> >> > ImmutableFooImmutableBarPair(myFoo,
> >> > > myBar);
> >> > > ...
> >> > > pair.getImmutableFoo();
> >> > > ...
> >> > > pair.getImmutableBar();
> >> > >
> >> > > Gary
> >> > >
> >> > >
> >> > >>
> >> > >> On Tue, Oct 22, 2013 at 12:15 PM, sebb <sebbaz@gmail.com>
wrote:
> >> > >>
> >> > >> > On 22 October 2013 18:10, Gary Gregory <garydgregory@gmail.com>
> >> > wrote:
> >> > >> > > Hi All:
> >> > >> > >
> >> > >> > > Is there any reason we would want to keep ImmutablePair
final?
> >> > >> >
> >> > >> > To stop mutable subclasses from being created?
> >> > >> >
> >> > >> > BTW, it's unfortunate that the fields are public; they should
> have
> >> > >> > been private (there are public getters).
> >> > >> >
> >> > >> > > Gary
> >> > >> > >
> >> > >> > > --
> >> > >> > > E-Mail: garydgregory@gmail.com | ggregory@apache.org
> >> > >> > > Java Persistence with Hibernate, Second Edition<
> >> > >> > http://www.manning.com/bauer3/>
> >> > >> > > JUnit in Action, Second Edition <
> http://www.manning.com/tahchiev/
> >> >
> >> > >> > > Spring Batch in Action <http://www.manning.com/templier/>
> >> > >> > > Blog: http://garygregory.wordpress.com
> >> > >> > > Home: http://garygregory.com/
> >> > >> > > Tweet! http://twitter.com/GaryGregory
> >> > >> >
> >> > >> >
> >> ---------------------------------------------------------------------
> >> > >> > To unsubscribe, e-mail: dev-unsubscribe@commons.apache.org
> >> > >> > For additional commands, e-mail: dev-help@commons.apache.org
> >> > >> >
> >> > >> >
> >> > >>
> >> > >>
> >> > >> --
> >> > >> Cheers,
> >> > >> Paul
> >> > >>
> >> > >
> >> > >
> >> > >
> >> > > --
> >> > > E-Mail: garydgregory@gmail.com | ggregory@apache.org
> >> > > Java Persistence with Hibernate, Second Edition<
> >> > http://www.manning.com/bauer3/>
> >> > > JUnit in Action, Second Edition <http://www.manning.com/tahchiev/>
> >> > > Spring Batch in Action <http://www.manning.com/templier/>
> >> > > Blog: http://garygregory.wordpress.com
> >> > > Home: http://garygregory.com/
> >> > > Tweet! http://twitter.com/GaryGregory
> >> >
> >> > ---------------------------------------------------------------------
> >> > To unsubscribe, e-mail: dev-unsubscribe@commons.apache.org
> >> > For additional commands, e-mail: dev-help@commons.apache.org
> >> >
> >> >
> >>
> >
> >
> >
> > --
> > E-Mail: garydgregory@gmail.com | ggregory@apache.org
> > Java Persistence with Hibernate, Second Edition<
> http://www.manning.com/bauer3/>
> > JUnit in Action, Second Edition <http://www.manning.com/tahchiev/>
> > Spring Batch in Action <http://www.manning.com/templier/>
> > Blog: http://garygregory.wordpress.com
> > Home: http://garygregory.com/
> > Tweet! http://twitter.com/GaryGregory
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: dev-unsubscribe@commons.apache.org
> For additional commands, e-mail: dev-help@commons.apache.org
>
>


-- 
E-Mail: garydgregory@gmail.com | ggregory@apache.org
Java Persistence with Hibernate, Second Edition<http://www.manning.com/bauer3/>
JUnit in Action, Second Edition <http://www.manning.com/tahchiev/>
Spring Batch in Action <http://www.manning.com/templier/>
Blog: http://garygregory.wordpress.com
Home: http://garygregory.com/
Tweet! http://twitter.com/GaryGregory

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