OK, this is a different design to one using Predicate, although obviously a
similar purpose. Before I can continue and finish the other collections, I
would like a decision on which way to go ;-)
This design gives much more power, but is therefore more complex (more
methods, more choice). Maybe there is a case for both. Maybe there is a case
for wrapping a Predicate in a CollectionFilter. Not quite sure yet.
I would suggest the following interface is necessary to fully express the
possibilities:
public interface CollectionFilter {
// predicate
public boolean allowUpdate(Object obj, Collection coll);
// transform
public Object beforeUpdate(Object obj, Collection coll);
// info
public void afterUpdate(Object obj, Collection coll);
// predicate
public boolean allowGet(Object obj, Collection coll);
// info ???
public void beforeGet(Object obj, Collection coll);
// transform
public Object afterGet(Object obj, Collection coll);
// predicate
public boolean allowRemove(Object obj, Collection coll);
// ???
public Object beforeRemove(Object obj, Collection coll);
// ???
public Object afterRemove(Object obj, Collection coll);
}
Hmm. Having sketched that out, I think I'm tending towards keeping it simple
and sticking with PredicateList and TransformList. Views? I need guidance on
this one before I can continue.
Stephen
From: Henri Yandell <[EMAIL PROTECTED]>
> public interface CollectionFilter {
>
> public Object beforeAdd(Object obj, Collection coll);
>
> public Object beforeRemove(Object obj, Collection coll);
> public Object afterRemove(Object obj, Collection coll);
>
> }
>
>
> And same (ish) for Map? And then List/Set extend Collection filter and add
> events?
>
> When something is added to the collection, it checks with beforeAdd,
> passing the object and the collection. In TypedFilter it is set to only
> allow Strings. It finds out the object isn't a String and returns null?
>
> But does that mean return or insert null. Can we have an interface that
> means both Predicate and Transform?? Or should they be separate.
>
> Hen
>
> > So we need something more than the existing Predicate/Transformer
classes
> > then? I think I need to go and code something to it working...
> > Stephen
>
>
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