On Thu, 1 Sep 2022 13:38:46 GMT, John Hendrikx <[email protected]> wrote:
>> modules/javafx.base/src/main/java/javafx/beans/value/ObservableValue.java
>> line 274:
>>
>>> 272: * <p>
>>> 273: * Returning {@code null} from the given condition is treated the
>>> same as
>>> 274: * returning {@code false}.
>>
>> I would rephrase to use the "holds" language instead of the "return":
>>
>>> `{@code condition}` holding `{@code null}` is treated the same as it
>>> holding `{@code false}`
>>
>> But is this the behavior we want? I would consider throwing when the
>> condition is not a `true` or `false` because it's a boolean condition.
>> `orElse` can be used to create a condition that maps `null` to something
>> else if the user wants to accept `null`s in the condition. I'm not sure if
>> this is really a problem.
>
> I've rephrased it as suggested.
>
> As for `null` -- I've clarified here what it currently does (so it is not
> left undefined), but I have no strong feelings either way.
>
> I mainly choose this direction because JavaFX has so far opted to treat
> `null` as something to be ignored or converted to a default value (for
> `BooleanProperty`, you can set it to `null` using the generic setter, and it
> would become `false`). Since the fluent system is basically built on top of
> `ObjectProperty` (and thus `Object`) we can't easily exclude the possibility
> of it being `null` (I have to accept `ObservableValue<Boolean>` instead of
> `BooleanProperty`).
>
> ie:
>
> listView.layoutXProperty().setValue(null);
>
> makes no sense at all, but JavaFX accepts it and uses `0.0`.
>
> Ouch, just noticed it always creates (not throws) an exception (with
> expensive stacktrace) whenever you do that, despite it maybe not getting
> logged:
>
> @Override
> public void setValue(Number v) {
> if (v == null) {
> Logging.getLogger().fine("Attempt to set double property to null,
> using default value instead.", new NullPointerException());
> set(0.0);
> } else {
> set(v.doubleValue());
> }
> }
Yeah, the behavior of the layout property is not the best in my opinion. Let's
see what others think.
-------------
PR: https://git.openjdk.org/jfx/pull/830
