RE: Move to JIRA [was: Re: [8u] API Request: RT-25613, ObservableValue should have a hasListener(listener) method]
Hi Anthony,
Thanks for sending a request for applying the multi-threaded plug-in.
As for the email plug-in mentioned below, using it does not mean sending all
JIRA's automatically to a single mailing list..
On the contrary it can be used as a selective tool for sharing selective JIRAs
to selective people/groups. This might be handy in case an issue was previously
discussed in JIRA and at a point you want to share with specific recipients.
Anyway if the current watch list mechanism functionality suffices that's it's
fine with me.. :)
Regards,
Seeon
-Original Message-
From: Anthony Petrov
Sent: Friday, January 24, 2014 1:07 PM
To: Seeon Birger; Steve Northover
Cc: John Hendrikx; openjfx-dev@openjdk.java.net
Subject: Re: Move to JIRA [was: Re: [8u] API Request: RT-25613, ObservableValue
should have a hasListener(listener) method]
Hi Seeon,
I don't think that posting updates from all our JIRAs to a single mailing list
is a good idea because the messages traffic would be huge.
Each JIRA provides a watch list, so people can follow specific bugs that
they're interested in. I believe that this functionality is sufficient for all
reasonable purposes.
However, your suggestion about using threaded comments sounds interesting.
We've sent a request to our Infrastructure team to evaluate the plugin and
consider adding it to our JIRA instance. Note that this is not going to happen
overnight and could take some time, but the request is filed at least. Thanks
for the suggestion!
--
best regards,
Anthony
On 1/23/2014 9:09 PM, Seeon Birger wrote:
Steve,
I wonder if we could take advantage of available plug-ins for JIRA.
I particular I found this one which enables threaded comments for JIRA:
https://marketplace.atlassian.com/plugins/com.atlassian.jira.threadedc
omments.threaded-comments
Also interesting is the following which make it easy to put JIRA updates on
mailing lists in a flexible and customizable way:
https://marketplace.atlassian.com/plugins/com.metainf.jira.plugin.emai
lissue
What do you think?
Seeon
-Original Message-
From: Stephen F Northover
Sent: Thursday, January 23, 2014 12:45 AM
To: John Hendrikx; openjfx-dev@openjdk.java.net
Subject: Re: Move to JIRA [was: Re: [8u] API Request: RT-25613,
ObservableValue should have a hasListener(listener) method]
Hi John,
The goal is not to end the discussion!
It's a trade off. Mailing lists are good because they provide a threaded
discussion. JIRA is bad because it is not threaded. JIRA has the advantage
that it captures data in a single place and provides a good history of why a
decision was made.
There's no right answer here but the policy that the FX committers is using
is to try to capture as much as possible in JIRA.
Steve
On 2014-01-22 5:29 PM, John Hendrikx wrote:
Unfortunately, discussing things in JIRA works very poorly and is a
good way to end a productive discussion IMHO. Mailinglists are much
better suited to the task, as thousands of interesting mailinglists
accross many developer communities will atest to.
Keeping a record is good, aren't these mailinglists archived?
--John
On 22/01/2014 18:47, Daniel Blaukopf wrote:
Hi Martin, Randahl, Tom, Richard, Tomas and Ali,
This is a productive discussion, but once we get to this level of
detail JIRA is the place to have it, so that we don't lose our
record of it. Would you continue the discussion on
https://javafx-jira.kenai.com/browse/RT-25613 ?
See
https://wiki.openjdk.java.net/display/OpenJFX/Code+Reviews#CodeRevie
w s-TechnicalDiscussionsandCodeReviews
Thanks,
Daniel
On Jan 22, 2014, at 7:23 PM, Stephen F
Northoversteve.x.northo...@oracle.com wrote:
If we add this API, I like addListener(InvalidationListener,
boolean) better than ensureListener().
Steve
On 2014-01-22 8:20 AM, Ali Ebrahimi wrote:
I suggest adding another overload for addListener method taking
boolean parameter duplicateAllowed or duplicateNotAllowed.
On Wed, Jan 22, 2014 at 3:00 PM, Richard
Bairrichard.b...@oracle.comwrote:
The default implementation (for Observable) would look like this:
public default void ensureListener(InvalidationListener listener) {
removeListener(listener);
addListener(listener);
}
subclasses might do something more effective. The same would
apply to ObservableValue and ChangeListener and
Observable[List|Set|Map] and [List|Set|Map]ChangeListener.
Well this would destroy the order! I expect listeners to be
called in the correct order not?
That's a good point :-(
Why doing a remove and not simply check if the
listener has already been added?
Because there is no way to check, except in the implementation.
From the
Observable interface level, there is no way to a) force all
implementations
of the interface to implement the method correctly (without
breaking source
compatibility anyway), or b) to provide a reasonable default
implementation.
Maybe
RE: Move to JIRA [was: Re: [8u] API Request: RT-25613, ObservableValue should have a hasListener(listener) method]
Steve,
I wonder if we could take advantage of available plug-ins for JIRA.
I particular I found this one which enables threaded comments for JIRA:
https://marketplace.atlassian.com/plugins/com.atlassian.jira.threadedcomments.threaded-comments
Also interesting is the following which make it easy to put JIRA updates on
mailing lists in a flexible and customizable way:
https://marketplace.atlassian.com/plugins/com.metainf.jira.plugin.emailissue
What do you think?
Seeon
-Original Message-
From: Stephen F Northover
Sent: Thursday, January 23, 2014 12:45 AM
To: John Hendrikx; openjfx-dev@openjdk.java.net
Subject: Re: Move to JIRA [was: Re: [8u] API Request: RT-25613, ObservableValue
should have a hasListener(listener) method]
Hi John,
The goal is not to end the discussion!
It's a trade off. Mailing lists are good because they provide a threaded
discussion. JIRA is bad because it is not threaded. JIRA has the advantage
that it captures data in a single place and provides a good history of why a
decision was made.
There's no right answer here but the policy that the FX committers is using is
to try to capture as much as possible in JIRA.
Steve
On 2014-01-22 5:29 PM, John Hendrikx wrote:
Unfortunately, discussing things in JIRA works very poorly and is a
good way to end a productive discussion IMHO. Mailinglists are much
better suited to the task, as thousands of interesting mailinglists
accross many developer communities will atest to.
Keeping a record is good, aren't these mailinglists archived?
--John
On 22/01/2014 18:47, Daniel Blaukopf wrote:
Hi Martin, Randahl, Tom, Richard, Tomas and Ali,
This is a productive discussion, but once we get to this level of
detail JIRA is the place to have it, so that we don't lose our record
of it. Would you continue the discussion on
https://javafx-jira.kenai.com/browse/RT-25613 ?
See
https://wiki.openjdk.java.net/display/OpenJFX/Code+Reviews#CodeReview
s-TechnicalDiscussionsandCodeReviews
Thanks,
Daniel
On Jan 22, 2014, at 7:23 PM, Stephen F
Northoversteve.x.northo...@oracle.com wrote:
If we add this API, I like addListener(InvalidationListener,
boolean) better than ensureListener().
Steve
On 2014-01-22 8:20 AM, Ali Ebrahimi wrote:
I suggest adding another overload for addListener method taking
boolean parameter duplicateAllowed or duplicateNotAllowed.
On Wed, Jan 22, 2014 at 3:00 PM, Richard
Bairrichard.b...@oracle.comwrote:
The default implementation (for Observable) would look like this:
public default void ensureListener(InvalidationListener listener) {
removeListener(listener);
addListener(listener);
}
subclasses might do something more effective. The same would
apply to
ObservableValue and ChangeListener and Observable[List|Set|Map] and
[List|Set|Map]ChangeListener.
Well this would destroy the order! I expect listeners to be
called in
the correct order not?
That's a good point :-(
Why doing a remove and not simply check if the
listener has already been added?
Because there is no way to check, except in the implementation.
From the
Observable interface level, there is no way to a) force all
implementations
of the interface to implement the method correctly (without
breaking source
compatibility anyway), or b) to provide a reasonable default
implementation.
Maybe this is one of those things we can't fix on the Observable
interface
and just have to provide implementations of on our concrete
properties.
Richard
[8u] API Request: RT-25613, ObservableValue should have a hasListener(listener) method
Hi all,
I would like to start discussion about an addition to API in Observable,
ObservableValue and all Observable collections.
There were multiple requests for a way how to avoid duplicates in
listeners lists. The way RT-25613 solves this is that it introduces
public boolean hasListener(ListenerType listener) which would return
true if the provided listener is already registered.
This has one significant drawback that all of Observable* are actually
interfaces. Means we can only add hasListener as a defender method. The
problem is with the default implementation. We cannot return anything
meaningful, so we have to throw an UnsupportedOperationException. The
problem is that this might blow up unexpectedly when some older
Observable implementation is used. Also, it might be easy to miss when
implementing the interface, since the IDE might not force you to
implement it.
So as an alternative solution, I propose adding something like:
ensureListener(ListenerType listener)
which would make sure the listener is on the list and if a listener is
already present, the number of times listener is registered on the
Observable will NOT grow after this call.
The default implementation (for Observable) would look like this:
public default void ensureListener(InvalidationListener listener) {
removeListener(listener);
addListener(listener);
}
subclasses might do something more effective. The same would apply to
ObservableValue and ChangeListener and Observable[List|Set|Map] and
[List|Set|Map]ChangeListener.
What do you think?
JIRA link: https://javafx-jira.kenai.com/browse/RT-25613
-Martin
Re: [8u] API Request: RT-25613, ObservableValue should have a hasListener(listener) method
Hi Martin
While I agree your proposed solution would work, I still don’t understand why
JavaFX should keep on supporting duplicates in listener collections. Can anyone
come up with just 1 example of an application that might be depending on having
two listeners on the same Observable? E.g. this kind of code:
myObservable.addListener(myChangeListener); //add it
myObservable.addListener(myChangeListener); //add it again
In what kind of situation would this sort of code make any sense?
If we all feel confident that the presence of duplicates listeners is always an
error, I warmly recommend changing the API to be duplicate free.
Yours
Randahl
On 22 Jan 2014, at 11:07, Martin Sladecek martin.slade...@oracle.com wrote:
Hi all,
I would like to start discussion about an addition to API in Observable,
ObservableValue and all Observable collections.
There were multiple requests for a way how to avoid duplicates in listeners
lists. The way RT-25613 solves this is that it introduces public boolean
hasListener(ListenerType listener) which would return true if the provided
listener is already registered.
This has one significant drawback that all of Observable* are actually
interfaces. Means we can only add hasListener as a defender method. The
problem is with the default implementation. We cannot return anything
meaningful, so we have to throw an UnsupportedOperationException. The problem
is that this might blow up unexpectedly when some older Observable
implementation is used. Also, it might be easy to miss when implementing the
interface, since the IDE might not force you to implement it.
So as an alternative solution, I propose adding something like:
ensureListener(ListenerType listener)
which would make sure the listener is on the list and if a listener is
already present, the number of times listener is registered on the Observable
will NOT grow after this call.
The default implementation (for Observable) would look like this:
public default void ensureListener(InvalidationListener listener) {
removeListener(listener);
addListener(listener);
}
subclasses might do something more effective. The same would apply to
ObservableValue and ChangeListener and Observable[List|Set|Map] and
[List|Set|Map]ChangeListener.
What do you think?
JIRA link: https://javafx-jira.kenai.com/browse/RT-25613
-Martin
Re: [8u] API Request: RT-25613, ObservableValue should have a hasListener(listener) method
The reason why this was decided this way is simple : performance. You
usually don't (try to) add a listener twice, so in most cases it doesn't
make sense to check for duplicates every time a listener is added. So we
currently leave the burden of avoiding duplicates on the developer.
-Martin
On 01/22/2014 11:23 AM, Randahl Fink Isaksen wrote:
Hi Martin
While I agree your proposed solution would work, I still don’t understand why
JavaFX should keep on supporting duplicates in listener collections. Can anyone
come up with just 1 example of an application that might be depending on having
two listeners on the same Observable? E.g. this kind of code:
myObservable.addListener(myChangeListener); //add it
myObservable.addListener(myChangeListener); //add it again
In what kind of situation would this sort of code make any sense?
If we all feel confident that the presence of duplicates listeners is always an
error, I warmly recommend changing the API to be duplicate free.
Yours
Randahl
On 22 Jan 2014, at 11:07, Martin Sladecek martin.slade...@oracle.com wrote:
Hi all,
I would like to start discussion about an addition to API in Observable,
ObservableValue and all Observable collections.
There were multiple requests for a way how to avoid duplicates in listeners
lists. The way RT-25613 solves this is that it introduces public boolean
hasListener(ListenerType listener) which would return true if the provided
listener is already registered.
This has one significant drawback that all of Observable* are actually interfaces. Means
we can only add hasListener as a defender method. The problem is with the default
implementation. We cannot return anything meaningful, so we have to throw an
UnsupportedOperationException. The problem is that this might blow up unexpectedly when
some older Observable implementation is used. Also, it might be easy to miss
when implementing the interface, since the IDE might not force you to implement it.
So as an alternative solution, I propose adding something like:
ensureListener(ListenerType listener)
which would make sure the listener is on the list and if a listener is already
present, the number of times listener is registered on the Observable will NOT
grow after this call.
The default implementation (for Observable) would look like this:
public default void ensureListener(InvalidationListener listener) {
removeListener(listener);
addListener(listener);
}
subclasses might do something more effective. The same would apply to
ObservableValue and ChangeListener and Observable[List|Set|Map] and
[List|Set|Map]ChangeListener.
What do you think?
JIRA link: https://javafx-jira.kenai.com/browse/RT-25613
-Martin
Re: [8u] API Request: RT-25613, ObservableValue should have a hasListener(listener) method
On 22.01.14 11:07, Martin Sladecek wrote:
Hi all,
I would like to start discussion about an addition to API in Observable,
ObservableValue and all Observable collections.
There were multiple requests for a way how to avoid duplicates in
listeners lists. The way RT-25613 solves this is that it introduces
public boolean hasListener(ListenerType listener) which would return
true if the provided listener is already registered.
This has one significant drawback that all of Observable* are actually
interfaces. Means we can only add hasListener as a defender method. The
problem is with the default implementation. We cannot return anything
meaningful, so we have to throw an UnsupportedOperationException. The
problem is that this might blow up unexpectedly when some older
Observable implementation is used. Also, it might be easy to miss when
implementing the interface, since the IDE might not force you to
implement it.
So as an alternative solution, I propose adding something like:
ensureListener(ListenerType listener)
which would make sure the listener is on the list and if a listener is
already present, the number of times listener is registered on the
Observable will NOT grow after this call.
The default implementation (for Observable) would look like this:
public default void ensureListener(InvalidationListener listener) {
removeListener(listener);
addListener(listener);
}
subclasses might do something more effective. The same would apply to
ObservableValue and ChangeListener and Observable[List|Set|Map] and
[List|Set|Map]ChangeListener.
Well this would destroy the order! I expect listeners to be called in
the correct order not? Why doing a remove and not simply check if the
listener has already been added?
Tom
Re: [8u] API Request: RT-25613, ObservableValue should have a hasListener(listener) method
Hi Martin
Then I respectfully disagree with this design decision. In my point of view,
choosing performance over ease of use is rarely a good idea. Here, the
performance choice has put us in a situation where no one knows how many JavaFX
apps have duplicate listener bugs, and such bugs can be very hard to debug.
Have anyone done any tests that prove that avoiding listener duplicates would
lead to a severe performance impact?
I understand, that if all observables had thousands of listeners and we
searched for a possible duplicate using an inefficient linear search, we would
have a problem. But if reality is that very few observables have more than 20
listeners and these could be stored in a map for efficient duplicate checking,
then what is the problem?
Yours
Randahl
On 22 Jan 2014, at 11:26, Martin Sladecek martin.slade...@oracle.com wrote:
The reason why this was decided this way is simple : performance. You usually
don't (try to) add a listener twice, so in most cases it doesn't make sense
to check for duplicates every time a listener is added. So we currently leave
the burden of avoiding duplicates on the developer.
-Martin
On 01/22/2014 11:23 AM, Randahl Fink Isaksen wrote:
Hi Martin
While I agree your proposed solution would work, I still don’t understand
why JavaFX should keep on supporting duplicates in listener collections. Can
anyone come up with just 1 example of an application that might be depending
on having two listeners on the same Observable? E.g. this kind of code:
myObservable.addListener(myChangeListener); //add it
myObservable.addListener(myChangeListener); //add it again
In what kind of situation would this sort of code make any sense?
If we all feel confident that the presence of duplicates listeners is always
an error, I warmly recommend changing the API to be duplicate free.
Yours
Randahl
On 22 Jan 2014, at 11:07, Martin Sladecek martin.slade...@oracle.com wrote:
Hi all,
I would like to start discussion about an addition to API in Observable,
ObservableValue and all Observable collections.
There were multiple requests for a way how to avoid duplicates in listeners
lists. The way RT-25613 solves this is that it introduces public boolean
hasListener(ListenerType listener) which would return true if the provided
listener is already registered.
This has one significant drawback that all of Observable* are actually
interfaces. Means we can only add hasListener as a defender method. The
problem is with the default implementation. We cannot return anything
meaningful, so we have to throw an UnsupportedOperationException. The
problem is that this might blow up unexpectedly when some older
Observable implementation is used. Also, it might be easy to miss when
implementing the interface, since the IDE might not force you to implement
it.
So as an alternative solution, I propose adding something like:
ensureListener(ListenerType listener)
which would make sure the listener is on the list and if a listener is
already present, the number of times listener is registered on the
Observable will NOT grow after this call.
The default implementation (for Observable) would look like this:
public default void ensureListener(InvalidationListener listener) {
removeListener(listener);
addListener(listener);
}
subclasses might do something more effective. The same would apply to
ObservableValue and ChangeListener and Observable[List|Set|Map] and
[List|Set|Map]ChangeListener.
What do you think?
JIRA link: https://javafx-jira.kenai.com/browse/RT-25613
-Martin
Re: [8u] API Request: RT-25613, ObservableValue should have a hasListener(listener) method
On 01/22/2014 11:27 AM, Tom Schindl wrote:
On 22.01.14 11:07, Martin Sladecek wrote:
Hi all,
I would like to start discussion about an addition to API in Observable,
ObservableValue and all Observable collections.
There were multiple requests for a way how to avoid duplicates in
listeners lists. The way RT-25613 solves this is that it introduces
public boolean hasListener(ListenerType listener) which would return
true if the provided listener is already registered.
This has one significant drawback that all of Observable* are actually
interfaces. Means we can only add hasListener as a defender method. The
problem is with the default implementation. We cannot return anything
meaningful, so we have to throw an UnsupportedOperationException. The
problem is that this might blow up unexpectedly when some older
Observable implementation is used. Also, it might be easy to miss when
implementing the interface, since the IDE might not force you to
implement it.
So as an alternative solution, I propose adding something like:
ensureListener(ListenerType listener)
which would make sure the listener is on the list and if a listener is
already present, the number of times listener is registered on the
Observable will NOT grow after this call.
The default implementation (for Observable) would look like this:
public default void ensureListener(InvalidationListener listener) {
removeListener(listener);
addListener(listener);
}
subclasses might do something more effective. The same would apply to
ObservableValue and ChangeListener and Observable[List|Set|Map] and
[List|Set|Map]ChangeListener.
Well this would destroy the order! I expect listeners to be called in
the correct order not? Why doing a remove and not simply check if the
listener has already been added?
Tom
Because there's no way to do it in the interface, hence the problem with
hasListener default implementation.
Yes, the order would be broken, but it's actually not guaranteed.
Although FX internally uses a List, 3rd party implementations of
Observable or ObservableValue might use a Set for listeners for example.
This was the idea, but funnily enough, the current Observable javadoc is
quite strict on the duplicates which would rule out the Set:
/**
* Adds an {@link InvalidationListener} which will be notified
whenever the
* {@code Observable} becomes invalid. If the same
* listener is added more than once, then it will be notified more than
* once. That is, no check is made to ensure uniqueness.
Personally, I would rather make this requirement less strict and allow
both List backed and Set backed implementations.
-Martin
Re: [8u] API Request: RT-25613, ObservableValue should have a hasListener(listener) method
On 01/22/2014 11:38 AM, Randahl Fink Isaksen wrote:
Hi Martin
Then I respectfully disagree with this design decision. In my point of view,
choosing performance over ease of use is rarely a good idea. Here, the
performance choice has put us in a situation where no one knows how many JavaFX
apps have duplicate listener bugs, and such bugs can be very hard to debug.
Have anyone done any tests that prove that avoiding listener duplicates would
lead to a severe performance impact?
I'm not the original author of the Observable API, but I remember there
were many performance tests back at the days before 2.0 release, esp.
when such API decision was made. So likely, the tests were done, but the
results were not archived or anything.
I understand, that if all observables had thousands of listeners and we
searched for a possible duplicate using an inefficient linear search, we would
have a problem. But if reality is that very few observables have more than 20
listeners and these could be stored in a map for efficient duplicate checking,
then what is the problem?
Well it's always a balance between performance, dynamic footprint (a
set/map for duplicates) and API. Having an API that extensively checks
for all the mistakes a developer can do is an extreme case in the same
manner as an API that does not check input at all. If a cleanup of some
listeners is missing, it's a developer's bug (memory leak) no matter if
there a duplicate listener check or not on the subsequent addListener
call when the object becomes valid again (or whatnot).
I understand your position, there are APIs I would also like to behave
differently, but the decision was already made, it's too late for the
discussion. There might be 3rd implementations that use a list a don't
guarantee a duplicate check, we don't want to make them suddenly broken.
I also disagree that such bugs are hard to debug, a simple printout
should do.
In many cases it would likely just make a computations run more times
than necessary. I can imagine doing a duplicate check on something like
-Djavafx.debug=true.
Regards,
-Martin
Yours
Randahl
On 22 Jan 2014, at 11:26, Martin Sladecek martin.slade...@oracle.com wrote:
The reason why this was decided this way is simple : performance. You usually
don't (try to) add a listener twice, so in most cases it doesn't make sense to
check for duplicates every time a listener is added. So we currently leave the
burden of avoiding duplicates on the developer.
-Martin
On 01/22/2014 11:23 AM, Randahl Fink Isaksen wrote:
Hi Martin
While I agree your proposed solution would work, I still don’t understand why
JavaFX should keep on supporting duplicates in listener collections. Can anyone
come up with just 1 example of an application that might be depending on having
two listeners on the same Observable? E.g. this kind of code:
myObservable.addListener(myChangeListener); //add it
myObservable.addListener(myChangeListener); //add it again
In what kind of situation would this sort of code make any sense?
If we all feel confident that the presence of duplicates listeners is always an
error, I warmly recommend changing the API to be duplicate free.
Yours
Randahl
On 22 Jan 2014, at 11:07, Martin Sladecek martin.slade...@oracle.com wrote:
Hi all,
I would like to start discussion about an addition to API in Observable,
ObservableValue and all Observable collections.
There were multiple requests for a way how to avoid duplicates in listeners
lists. The way RT-25613 solves this is that it introduces public boolean
hasListener(ListenerType listener) which would return true if the provided
listener is already registered.
This has one significant drawback that all of Observable* are actually interfaces. Means
we can only add hasListener as a defender method. The problem is with the default
implementation. We cannot return anything meaningful, so we have to throw an
UnsupportedOperationException. The problem is that this might blow up unexpectedly when
some older Observable implementation is used. Also, it might be easy to miss
when implementing the interface, since the IDE might not force you to implement it.
So as an alternative solution, I propose adding something like:
ensureListener(ListenerType listener)
which would make sure the listener is on the list and if a listener is already
present, the number of times listener is registered on the Observable will NOT
grow after this call.
The default implementation (for Observable) would look like this:
public default void ensureListener(InvalidationListener listener) {
removeListener(listener);
addListener(listener);
}
subclasses might do something more effective. The same would apply to
ObservableValue and ChangeListener and Observable[List|Set|Map] and
[List|Set|Map]ChangeListener.
What do you think?
JIRA link: https://javafx-jira.kenai.com/browse/RT-25613
-Martin
Re: [8u] API Request: RT-25613, ObservableValue should have a hasListener(listener) method
Hi Randahl,
I'm curious about an example where you would take advantage of the behavior
where multiple addListener(listener) calls add the listener just once.
Anyway, here [1] are helper classes InvalidationSubscriber and
ChangeSubscriber that allow you to do that:
InvalidationSubscriber subscriber = new InvalidationSubscriber(observable,
listener);
subscriber.subscribe(); // registers the listener
subscriber.subscribe(); // no-op
Cheers,
Tomas
[1] https://gist.github.com/TomasMikula/8557825
On Wed, Jan 22, 2014 at 11:23 AM, Randahl Fink Isaksen rand...@rockit.dkwrote:
Hi Martin
While I agree your proposed solution would work, I still don’t understand
why JavaFX should keep on supporting duplicates in listener collections.
Can anyone come up with just 1 example of an application that might be
depending on having two listeners on the same Observable? E.g. this kind of
code:
myObservable.addListener(myChangeListener); //add it
myObservable.addListener(myChangeListener); //add it again
In what kind of situation would this sort of code make any sense?
If we all feel confident that the presence of duplicates listeners is
always an error, I warmly recommend changing the API to be duplicate free.
Yours
Randahl
On 22 Jan 2014, at 11:07, Martin Sladecek martin.slade...@oracle.com
wrote:
Hi all,
I would like to start discussion about an addition to API in Observable,
ObservableValue and all Observable collections.
There were multiple requests for a way how to avoid duplicates in
listeners lists. The way RT-25613 solves this is that it introduces public
boolean hasListener(ListenerType listener) which would return true if the
provided listener is already registered.
This has one significant drawback that all of Observable* are actually
interfaces. Means we can only add hasListener as a defender method. The
problem is with the default implementation. We cannot return anything
meaningful, so we have to throw an UnsupportedOperationException. The
problem is that this might blow up unexpectedly when some older
Observable implementation is used. Also, it might be easy to miss when
implementing the interface, since the IDE might not force you to implement
it.
So as an alternative solution, I propose adding something like:
ensureListener(ListenerType listener)
which would make sure the listener is on the list and if a listener is
already present, the number of times listener is registered on the
Observable will NOT grow after this call.
The default implementation (for Observable) would look like this:
public default void ensureListener(InvalidationListener listener) {
removeListener(listener);
addListener(listener);
}
subclasses might do something more effective. The same would apply to
ObservableValue and ChangeListener and Observable[List|Set|Map] and
[List|Set|Map]ChangeListener.
What do you think?
JIRA link: https://javafx-jira.kenai.com/browse/RT-25613
-Martin
Re: [8u] API Request: RT-25613, ObservableValue should have a hasListener(listener) method
[...] Actually even when you would rely on the order, in situations when you call ensureListener, you don't really know if the listener is already there. So you might really expect that listener would be added at this point as the last. It's just that will always be the outcome if the default implementation is used. It would be even worse if this would be different in none default implementations. Tom
Re: [8u] API Request: RT-25613, ObservableValue should have a hasListener(listener) method
I suggest adding another overload for addListener method taking boolean
parameter duplicateAllowed or duplicateNotAllowed.
On Wed, Jan 22, 2014 at 3:00 PM, Richard Bair richard.b...@oracle.comwrote:
The default implementation (for Observable) would look like this:
public default void ensureListener(InvalidationListener listener) {
removeListener(listener);
addListener(listener);
}
subclasses might do something more effective. The same would apply to
ObservableValue and ChangeListener and Observable[List|Set|Map] and
[List|Set|Map]ChangeListener.
Well this would destroy the order! I expect listeners to be called in
the correct order not?
That’s a good point :-(
Why doing a remove and not simply check if the
listener has already been added?
Because there is no way to check, except in the implementation. From the
Observable interface level, there is no way to a) force all implementations
of the interface to implement the method correctly (without breaking source
compatibility anyway), or b) to provide a reasonable default implementation.
Maybe this is one of those things we can’t fix on the Observable interface
and just have to provide implementations of on our concrete properties.
Richard
Move to JIRA [was: Re: [8u] API Request: RT-25613, ObservableValue should have a hasListener(listener) method]
Hi Martin, Randahl, Tom, Richard, Tomas and Ali,
This is a productive discussion, but once we get to this level of detail JIRA
is the place to have it, so that we don’t lose our record of it. Would you
continue the discussion on https://javafx-jira.kenai.com/browse/RT-25613 ?
See
https://wiki.openjdk.java.net/display/OpenJFX/Code+Reviews#CodeReviews-TechnicalDiscussionsandCodeReviews
Thanks,
Daniel
On Jan 22, 2014, at 7:23 PM, Stephen F Northover steve.x.northo...@oracle.com
wrote:
If we add this API, I like addListener(InvalidationListener, boolean) better
than ensureListener().
Steve
On 2014-01-22 8:20 AM, Ali Ebrahimi wrote:
I suggest adding another overload for addListener method taking boolean
parameter duplicateAllowed or duplicateNotAllowed.
On Wed, Jan 22, 2014 at 3:00 PM, Richard Bair richard.b...@oracle.comwrote:
The default implementation (for Observable) would look like this:
public default void ensureListener(InvalidationListener listener) {
removeListener(listener);
addListener(listener);
}
subclasses might do something more effective. The same would apply to
ObservableValue and ChangeListener and Observable[List|Set|Map] and
[List|Set|Map]ChangeListener.
Well this would destroy the order! I expect listeners to be called in
the correct order not?
That’s a good point :-(
Why doing a remove and not simply check if the
listener has already been added?
Because there is no way to check, except in the implementation. From the
Observable interface level, there is no way to a) force all implementations
of the interface to implement the method correctly (without breaking source
compatibility anyway), or b) to provide a reasonable default implementation.
Maybe this is one of those things we can’t fix on the Observable interface
and just have to provide implementations of on our concrete properties.
Richard
Re: Move to JIRA [was: Re: [8u] API Request: RT-25613, ObservableValue should have a hasListener(listener) method]
Unfortunately, discussing things in JIRA works very poorly and is a
good way to end a productive discussion IMHO. Mailinglists are much
better suited to the task, as thousands of interesting mailinglists
accross many developer communities will atest to.
Keeping a record is good, aren't these mailinglists archived?
--John
On 22/01/2014 18:47, Daniel Blaukopf wrote:
Hi Martin, Randahl, Tom, Richard, Tomas and Ali,
This is a productive discussion, but once we get to this level of detail JIRA
is the place to have it, so that we don’t lose our record of it. Would you
continue the discussion on https://javafx-jira.kenai.com/browse/RT-25613 ?
See
https://wiki.openjdk.java.net/display/OpenJFX/Code+Reviews#CodeReviews-TechnicalDiscussionsandCodeReviews
Thanks,
Daniel
On Jan 22, 2014, at 7:23 PM, Stephen F Northoversteve.x.northo...@oracle.com
wrote:
If we add this API, I like addListener(InvalidationListener, boolean) better
than ensureListener().
Steve
On 2014-01-22 8:20 AM, Ali Ebrahimi wrote:
I suggest adding another overload for addListener method taking boolean
parameter duplicateAllowed or duplicateNotAllowed.
On Wed, Jan 22, 2014 at 3:00 PM, Richard Bairrichard.b...@oracle.comwrote:
The default implementation (for Observable) would look like this:
public default void ensureListener(InvalidationListener listener) {
removeListener(listener);
addListener(listener);
}
subclasses might do something more effective. The same would apply to
ObservableValue and ChangeListener and Observable[List|Set|Map] and
[List|Set|Map]ChangeListener.
Well this would destroy the order! I expect listeners to be called in
the correct order not?
That’s a good point :-(
Why doing a remove and not simply check if the
listener has already been added?
Because there is no way to check, except in the implementation. From the
Observable interface level, there is no way to a) force all implementations
of the interface to implement the method correctly (without breaking source
compatibility anyway), or b) to provide a reasonable default implementation.
Maybe this is one of those things we can’t fix on the Observable interface
and just have to provide implementations of on our concrete properties.
Richard
Re: Move to JIRA [was: Re: [8u] API Request: RT-25613, ObservableValue should have a hasListener(listener) method]
The point is that we'd rather have quick reference to the historical
discussion without having to cross-reference between jira and the
mailing list archives (which isn't automatically done). Once you add
yourself as a watcher to the jira issue you are notified of every
change, in much the same way as you are emailed of the discussion on
this mailing list.
A good case in point came up just today with Martin referencing
historical choices made with the Observable API, but not being able to
reference them as they are not recorded anywhere (and if they are, being
able to search for them is not trivial - the only hope is to find them
in your email client and then go off to the openjfx-dev archives and
manually search through the discussions until the right thread is
found). Whilst Jira search isn't great, it is better than this!
In other words, I can see an upside without any downside. What troubles
do you have with Jira specifically?
-- Jonathan
On 23/01/2014 11:29 a.m., John Hendrikx wrote:
Unfortunately, discussing things in JIRA works very poorly and is a
good way to end a productive discussion IMHO. Mailinglists are much
better suited to the task, as thousands of interesting mailinglists
accross many developer communities will atest to.
Keeping a record is good, aren't these mailinglists archived?
--John
On 22/01/2014 18:47, Daniel Blaukopf wrote:
Hi Martin, Randahl, Tom, Richard, Tomas and Ali,
This is a productive discussion, but once we get to this level of
detail JIRA is the place to have it, so that we don’t lose our record
of it. Would you continue the discussion on
https://javafx-jira.kenai.com/browse/RT-25613 ?
See
https://wiki.openjdk.java.net/display/OpenJFX/Code+Reviews#CodeReviews-TechnicalDiscussionsandCodeReviews
Thanks,
Daniel
On Jan 22, 2014, at 7:23 PM, Stephen F
Northoversteve.x.northo...@oracle.com wrote:
If we add this API, I like addListener(InvalidationListener,
boolean) better than ensureListener().
Steve
On 2014-01-22 8:20 AM, Ali Ebrahimi wrote:
I suggest adding another overload for addListener method taking
boolean
parameter duplicateAllowed or duplicateNotAllowed.
On Wed, Jan 22, 2014 at 3:00 PM, Richard
Bairrichard.b...@oracle.comwrote:
The default implementation (for Observable) would look like this:
public default void ensureListener(InvalidationListener listener) {
removeListener(listener);
addListener(listener);
}
subclasses might do something more effective. The same would
apply to
ObservableValue and ChangeListener and Observable[List|Set|Map] and
[List|Set|Map]ChangeListener.
Well this would destroy the order! I expect listeners to be
called in
the correct order not?
That’s a good point :-(
Why doing a remove and not simply check if the
listener has already been added?
Because there is no way to check, except in the implementation.
From the
Observable interface level, there is no way to a) force all
implementations
of the interface to implement the method correctly (without
breaking source
compatibility anyway), or b) to provide a reasonable default
implementation.
Maybe this is one of those things we can’t fix on the Observable
interface
and just have to provide implementations of on our concrete
properties.
Richard
Re: Move to JIRA [was: Re: [8u] API Request: RT-25613, ObservableValue should have a hasListener(listener) method]
Hi John,
The goal is not to end the discussion!
It's a trade off. Mailing lists are good because they provide a
threaded discussion. JIRA is bad because it is not threaded. JIRA has
the advantage that it captures data in a single place and provides a
good history of why a decision was made.
There's no right answer here but the policy that the FX committers is
using is to try to capture as much as possible in JIRA.
Steve
On 2014-01-22 5:29 PM, John Hendrikx wrote:
Unfortunately, discussing things in JIRA works very poorly and is a
good way to end a productive discussion IMHO. Mailinglists are much
better suited to the task, as thousands of interesting mailinglists
accross many developer communities will atest to.
Keeping a record is good, aren't these mailinglists archived?
--John
On 22/01/2014 18:47, Daniel Blaukopf wrote:
Hi Martin, Randahl, Tom, Richard, Tomas and Ali,
This is a productive discussion, but once we get to this level of
detail JIRA is the place to have it, so that we don’t lose our record
of it. Would you continue the discussion on
https://javafx-jira.kenai.com/browse/RT-25613 ?
See
https://wiki.openjdk.java.net/display/OpenJFX/Code+Reviews#CodeReviews-TechnicalDiscussionsandCodeReviews
Thanks,
Daniel
On Jan 22, 2014, at 7:23 PM, Stephen F
Northoversteve.x.northo...@oracle.com wrote:
If we add this API, I like addListener(InvalidationListener,
boolean) better than ensureListener().
Steve
On 2014-01-22 8:20 AM, Ali Ebrahimi wrote:
I suggest adding another overload for addListener method taking
boolean
parameter duplicateAllowed or duplicateNotAllowed.
On Wed, Jan 22, 2014 at 3:00 PM, Richard
Bairrichard.b...@oracle.comwrote:
The default implementation (for Observable) would look like this:
public default void ensureListener(InvalidationListener listener) {
removeListener(listener);
addListener(listener);
}
subclasses might do something more effective. The same would
apply to
ObservableValue and ChangeListener and Observable[List|Set|Map] and
[List|Set|Map]ChangeListener.
Well this would destroy the order! I expect listeners to be
called in
the correct order not?
That’s a good point :-(
Why doing a remove and not simply check if the
listener has already been added?
Because there is no way to check, except in the implementation.
From the
Observable interface level, there is no way to a) force all
implementations
of the interface to implement the method correctly (without
breaking source
compatibility anyway), or b) to provide a reasonable default
implementation.
Maybe this is one of those things we can’t fix on the Observable
interface
and just have to provide implementations of on our concrete
properties.
Richard
