On 07.11.2007, at 04:54, Niall Pemberton wrote:
On Oct 21, 2007 7:12 AM, Mario Ivankovits <[EMAIL PROTECTED]> wrote:
Hi!
Maybe it would make more sense to do these changes in commons-
jci-fam
first and then move that to a new commons-fam?
Sounds reasonable, although I still think IO is a better home for
fam
than a separate component.
In any case, it would be creat if the code is built in a way that
makes
it possible to plug VFS in there too. The VFS fam is far from being
perfect :-(
I'm not sure how this would be possible - since we would need to
abstract away from java.io.File - which is exactly what VFS does. For
me theres value in a "closer to the metal" impl. that just deals with
java.io.File and an abstract VFS version.
Well, one thought would be to use generics. The JCI monitor expects a
very simple interface that both the native java.io.File and the VFS
abstraction share. (see FilesystemAlterationObserverImpl.MonitorFile)
private interface MonitorFile {
long lastModified();
MonitorFile[] listFiles();
boolean isDirectory();
boolean exists();
String getName();
}
The problem here is that in java you need to explicitly implement an
interface to be compatible with the interface (not just implement the
methods described through it). So while this would work
public FilesystemAlterationListener<E extends MonitorFile> {
onFileChange(E file)
...
}
public class FAM<E extends MonitorFile> {
...
}
and VFS could just implement the MonitorFile
interface ...java.io.File cannot (although it actually does). I fear
the only way to share the same code would be
a) through reflection
b) have VFS extend the java.io.File class. But I guess we already
agreed in the "compress" thread that is not really a good idea.
c) use the interface in the Listener
public FilesystemAlterationListener<E extends MonitorFile> {
onFileChange(MonitorFile file) {
File f = (File) file.getImpl(); // UGLY!!
}
...
}
but that sucks as you cannot get to the actual implementation
easily.
Thoughts?
cheers
--
Torsten
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