On Aug 8, 2009, at 10:57 PM, Marshall Schor wrote:
Jörn Kottmann wrote:
On Aug 7, 2009, at 8:57 PM, Marshall Schor wrote:
getViewIterator in CASImpl is written with the signature:
Iterator<CAS> getViewIterator()
If you are working with things needing CASImpl objects, you would
write:
Iterator<CAS> s = aCas.getViewIterator();
while (s.hasNext()) {
CASImpl ci = (CASImpl) s.next();
... code using ci...
}
If we changed the signature to:
Iterator<T extends CAS> getViewIterator()
then you would write:
Iterator<CASImpl> s = aCas.getViewIterator(); // cast done inside
the
support code, not here
while (s.hasNext()) {
CASImpl ci = s.next(); // works OK without casting
... code using ci...
}
Would it be better to have that form of the signature?
+1, though did not know that its possible, we should check other
places too
+1 to checking other places :-)
The tutorial on generics by Gilad Bracha,
http://java.sun.com/j2se/1.5/pdf/generics-tutorial.pdf, on page 20
near
the top says:
In general, if you have an API that only uses a type parameter T as
an
argument, its
uses should take advantage of lower bounded wildcards (? super T).
Conversely, if
the API only returns T, you’ll give your clients more flexibility by
using upper bounded
wildcards (? extends T).
There are many cases I think in our generification where the 2nd
part of
this, returning XXX<? extends T> or a variant, is a better choice.
In the end we can do this generification for all methods which
return an object of a type which is declared by an UIMA interface,
right ?
Jörn
