+1 to doing something like this. I just recently discovered FXCollections.concat(ObservableList…) doesn’t do what you propose. I figured that was the whole point.
Scott On Dec 31, 2022, at 3:44 PM, Nir Lisker <nlis...@gmail.com> wrote:
We can do better than that. Instead of introducing methods for specific operations, like concat and retain, we can offer bulk operations on collections. When John H. proposed the fluent bindings additions, we discussed doing the same for collections after that.
At the very least, we can have a method that takes an observable collection and a function that specifies the operation you want to perform. This will be a lot more flexible.
I have been playing around with adding ObservableCollection as a first step so that we don't need to multiply the methods for sets and lists. It's also useful for an observableValues() on ObservableMap. I hit a few backwards compatibility issues there.
I can share later some mock API I created as a sort of end goal, but it's incomplete. FXCollections.concat(ObservableList...) can be used to create a new
ObservableList that contains the concatenation of all elements of the
source lists. This is useful to initialize the contents of the new
ObservableList, but the returned list is not kept in sync with the
source lists.
I'm proposing to add a new method:
FXCollections.concatenatedObservableList(ObservableList...)
Like FXCollections.concat, it returns a list that contains the
concatenation of all elements of the source lists. However, in this
case the returned list is unmodifiable and is always kept in sync with
the source lists. This can be useful to create a list where only parts
of the list are under the control of the author, and other parts are
derived from other lists.
I'm interested to hear your thoughts on this. Here's the proposed
specification of the new method:
/**
* Creates a new unmodifiable {@code ObservableList} that contains
* the concatenation of the contents of the specified observable lists.
* In contrast to {@link #concat(ObservableList[])}, the list returned from
* this method is updated when any of the source lists are changed.
*
* @param lists the source lists
* @param <E> the element type
* @return an {@code ObservableList} that contains the concatenation
* of the contents of {@code lists}
* @throws IndexOutOfBoundsException if the sum of the number of
* elements contained in all source lists exceeds
* {@link Integer#MAX_VALUE}
*/
@SafeVarargs
public static <E> ObservableList<E> concatenatedObservableList(
ObservableList<E>... lists)
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