On Tuesday 26 March 2002 19:26 pm, Dominique Devienne wrote:
> Then how about using Containment instead of Inheritance? That way, you can
> create a brand new instance of the Task you delegate to, and initialize it
> to your heart's desire.
Absolutely, it's just a lot of extra work ;). In fact, that's currently the
only way to do it without making changes to any class other than mine.
> Of course, it's more typing to you, if you want to
> expose setters/adders/creaters of the contained task. And you need your own
> execute() method... I'm assuming it's easy to create the task
i'm overriding execute(), but not having getters to work with is a limitation
i've run into several times in trying to make use of Task objects. They are
not very subclassable, but this is apparently by-design. The lack of getters
makes the objects difficult or impossible to use via delagation in some
cases, and makes subclassing them a hassle because one must override the
setter if he needs access to one of the not-yet-accessible data members:
public void setFoo( boolean foo ) { this.foo = foo; super.setFoo( foo ); }
(And then i supply a getter, since the poor bastard using the object next
time might be me.)
This overriding of setters is Not a Good Idea (let's even call it a Very Bad
Idea), because we cannot be guaranteed that the object passed to us
is the actual object used by super.setFoo(). Perhaps it makes a copy and
manipulates it in some way? Perhaps it sets it's value directly, internally,
which makes our copy out-of-sync (for primitive types, anyway)? It's
dangerous, but only because the ant classes always reference their data
directly - accessing even internal data ONLY via get/set methods makes all
the difference in the world when subclassing. It solves a number of problems
at the relatively small expense of another function call.
> programmatically, which I don't see why it shouldn't be given all the
> reflection ANT is doing (and my experience hasking ANT 1.3 back then).
> FWIW, --DD
That's an excellent point - why hide the data if Java will give it to you, so
long as you ask nicely? ;)
----- stephan
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