Because mutable objects are evil. It would for example make it impossible to
write classes like this:
class Person {
private final Expansion<Node> friends;
Person(Node node) {
this.friends = node.expand( FRIEND ).nodes();
}
Iterable<Person> getFriends() {
return persons( friends );
}
Iterable<Person> getFriends( final int minimumAge ) {
return persons( friends.filterNodes( new Predicate<Node>() {
public boolean accept(Node friend) {
return minimumAge >= (Integer)friend.getProperty("age");
}
}) );
}
static Iterable<Person> persons( Iterable<Node> persons ) {
return IterableWrapper<Person, Node>( persons ) {
protected Person underlyingObjectToObject( Node person ) {
return new Person( person );
}
}
}
}
This might be an acceptable loss though. This could be a case where it is ok
to reuse the same object and mutate the internal state. It's something to
think about...
-tobias
On Wed, Jun 23, 2010 at 7:10 PM, Craig Taverner <cr...@amanzi.com> wrote:
> Why not have includes() return the same instance with internal state
> changed, then the various call options are equivalent.
>
> On Jun 23, 2010 6:41 PM, "Tobias Ivarsson" <
> tobias.ivars...@neotechnology.com> wrote:
>
> On Wed, Jun 23, 2010 at 6:10 PM, Craig Taverner <cr...@amanzi.com> wrote:
> >
> > (I also noticed that r...
> I get that feeling as well. Another feeling I get with includes() is that
> it
> might be possible to do the following:
>
>
> Expansion<Relationship> expansion = startNode.expand( KNOWS );
> expansion.includes( LIKES );
> expansion.includes( LOVES );
> for (Node node : expansion.nodes()) {
> ...
> }
>
> With includes() one gets the feeling that the above would expand LOVES,
> LIKES and KNOWS relationships, but it will in fact only expand KNOWS
> relationships. With and() I don't think that mistake would be as common.
>
> Cheers,
> --
>
> Tobias Ivarsson <tobias.ivars...@neotechnology.com>
> Hacker, Neo Technology
> www.neotechnology.com
> Cel...
> _______________________________________________
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>
--
Tobias Ivarsson <tobias.ivars...@neotechnology.com>
Hacker, Neo Technology
www.neotechnology.com
Cellphone: +46 706 534857
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