Hi.
On Fri, 20 Jul 2018 09:47:21 +0100, sebb wrote:
On 20 July 2018 at 00:09, Bruno P. Kinoshita
<brunodepau...@yahoo.com.br.invalid> wrote:
What is the replacement for Observer/Observable recommended by
the JDK developers?
I believe they suggest to use the PropertyListener which we have
right now, but are in the java.beans module I think.
Alternatively, they also suggest in the javadocs to look into the
java.util.concurrent package if concurrency is important.
From what I understand about the latter option, it would mean
building your own event-bus or listeners.
I've read that Observer/Observable will not be removed from the
JDK (but won't be maintained). So, if the shortcomings are OK
for the purpose at hand, the issue is only the deprecation warning.
Does someone readily knows how to go about implementing an equivalent
functionality with "java.util.concurrent" classes?
Regards,
Gilles
As for the java.beans, a possible solution to avoid deprecation
right now would be include the java.beans property listeners code in
[lang]. Maybe internal only.
AFAIK we cannot copy any JVM code into our codebase, even if marked
internal.
It would have to be a clean-room implementation.
Bruno
From: Gilles <gil...@harfang.homelinux.org>
To: dev@commons.apache.org
Sent: Friday, 20 July 2018 11:05 AM
Subject: Re: [LANG] Java 9 problems because of dependencies to
java.desktop
Hello.
On Mon, 16 Jul 2018 21:30:00 +0000 (UTC), Bruno P. Kinoshita wrote:
What about introducing our own state listener interface? The
original
interface from the beans package was used just for convenience
because
it already existed. But it would of course be possible to have a
simple
functional interface to notify listeners about state changes.
Hmmm, that's an option as well.
Looks like they had the beans interface which we used, then later
we
had the java.util.Observable for a while, and now they are
suggesting
users to move to the beans interface, as one of the alternatives.
As some Java 9 users possibly wouldn't want to import the
java.beans
module, perhaps having this new interface could be an interesting
alternative.
I believe we would have to
[ ] decide whether to introduce an interface similar to
PropertyListener, or to Observable[ ] if the backward compatibility
changed, we must deprecate the existing classes
[ ] release a new version of lang with this new interface and the
updated circuit breakers[ ] and either delete the deprecated
classes
or leave it until for some more releases
I wonder what others think about this option?
What is the replacement for Observer/Observable recommended by
the JDK developers?
Regards,
Gilles
Cheers
Bruno
From: Oliver Heger <oliver.he...@oliver-heger.de>
To: dev@commons.apache.org
Sent: Tuesday, 17 July 2018 4:13 AM
Subject: Re: [LANG] Java 9 problems because of dependencies to
java.desktop (Was: Re: [LANG] Thoughts about Lang 4.0)
Am 16.07.2018 um 13:40 schrieb Bruno P. Kinoshita:
Saw some recent activity around lang 3.8, and remembered about
this
issue, and then looked for this thread.
Gilles' point is really good! Here's the Java 9 docs with the
deprecation warning, copied below as well
https://docs.oracle.com/javase/9/docs/api/index.html?java/util/Observable.html
"This class and the Observer interface have been deprecated. The
event model supported by Observer and Observable is quite limited,
the
order of notifications delivered by Observable is unspecified, and
state changes are not in one-for-one correspondence with
notifications. For a richer event model, consider using the
java.beans
package. For reliable and ordered messaging among threads,
consider
using one of the concurrent data structures in the
java.util.concurrent package. For reactive streams style
programming,
see the Flow API."
So I guess the best we can do right now is add the @deprecated
annotations, with an explanation in the javadocs. And also add a
note
about it in the release notes.
Does that sound like a good plan? Adding a link to this thread in
the pull request as well.
What about introducing our own state listener interface? The
original
interface from the beans package was used just for convenience
because
it already existed. But it would of course be possible to have a
simple
functional interface to notify listeners about state changes.
Oliver
Cheers
Bruno
________________________________
From: Stephen Colebourne <scolebou...@joda.org>
To: Commons Developers List <dev@commons.apache.org>
Sent: Monday, 11 June 2018 9:26 AM
Subject: Re: [LANG] Java 9 problems because of dependencies to
java.desktop (Was: Re: [LANG] Thoughts about Lang 4.0)
Good spot. I think that means [lang] would have to have its own
copy
of the JDK interfaces. or just deprecate the functionality without
replacement.
Stephen
On 10 June 2018 at 22:11, Gilles <gil...@harfang.homelinux.org>
wrote:
Hello.
On Sun, 10 Jun 2018 21:34:49 +0200, Oliver Heger wrote:
Hi Bruno,
Am 10.06.2018 um 00:52 schrieb Bruno P. Kinoshita:
Hi all,
There is a patch [1] for LANG-1339 [2] that I would like to
merge. The
discussion around this issue can be found in the rest of this
e-mail thread.
The patch basically deprecates the existing classes that depend
on
java.desktop, and provide alternative implementations. The
previous classes
used java.desktop classes for the PropertyChangeListener. And
the
alternative ones instead use Java 7's java.util.Observer.
Is it a good idea to use deprecated classes[1] in new code?
Regards,
Gilles
[1]
https://docs.oracle.com/javase/9/docs/api/java/util/Observable.html
This will make it easier to provide [lang] as java 9, without
requiring
users to include a dependency to java.desktop.
Planning to merge it during the next week if there are no
objections
here.
Thanks,
Bruno
agreed. This seems to be the best what we can do.
Oliver
[1] https://github.com/apache/commons-lang/pull/275
[2] https://issues.apache.org/jira/browse/LANG-1339
________________________________From: Benedikt Ritter
<brit...@apache.org>
To: Commons Developers List <dev@commons.apache.org>
Sent: Monday, 5 June 2017 10:49 PM
Subject: [LANG] Java 9 problems because of dependencies to
java.desktop
(Was: Re: [LANG] Thoughts about Lang 4.0)
Am 25.05.2017 um 18:23 schrieb Oliver Heger
<oliver.he...@oliver-heger.de>:
Am 24.05.2017 um 13:55 schrieb Stephen Colebourne:
On 23 May 2017 at 17:17, sebb <seb...@gmail.com> wrote:
Yes, the
code compiles and both can be on the classpath, but it is a
pain to
use, just a different kind of hell.
I don't see what the problem is here.
Library A that depends on lang3 returns a Pair.
Library B that depends on lang4 takes a Pair.
Application cannot pass Pair from A to the B without
conversion.
My point is that it is possible to over-worry about jar hell.
Joda-Time removed some methods when it went from v1.x to
v2.x,
but
didn't change package name or maven co-ordinates. It was far
more
important that end-users didn't have two different LocalDate
classes
(a problem that couldn't be avoided when moving to Java 8).
I've never
seen any feedback about the incompatibility causing jar hell.
The same is true here. It is vital to think properly about
which is
the worse choice, not just assume that jar hell must always
be
avoided.
I remain completely unconvinced that removing these two
problematic
methods justifies the lang4 package name, forcing end-users
to
have
three copies of the library on the classpath. It should need
much,
much more to justify lang4 package name. In fact I've yet to
hear
anything else much in this thread that justifies a major
release.
I also think that a new major release just to fix this problem
would be
overkill and cause clients even more trouble.
Would the following approach work as a compromise:
- [lang] declares an optional dependency to the desktop
module.
- All affected classes (AbstractCircuitBreaker and its two sub
classes)
are marked as deprecated.
- Copies are created from the original classes with slightly
changed
names or in a new package (tbd). These copies use a new change
listener
mechanism.
IIUC, the resulting [lang] module can now be used without the
dependency
to desktop when the new classes are used. The dependency will
only be
needed for the deprecated versions.
Let’s do it like this. Sounds like the right way to me.
Benedikt
Oliver
Stephen
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