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From Noel Grandin <noelgran...@gmail.com>
Subject Re: Disabling tree nodes, table rows, and list items
Date Wed, 29 Jul 2009 15:53:45 GMT
Great idea. Indexes are very hard to work with once you have widgets
that support sorting.

On 07/29/2009, Greg Brown <gkbrown@mac.com> wrote:
> By the way, the Filter interface would also have applications
> elsewhere, such as in a org.apache.pivot.collections.FilteredList
> class. This class would implement the List interface and would
> internally maintain a filtered copy of the source data, allowing it to
> be used as the model of a table view and independently sorted, etc.
>
> On Jul 29, 2009, at 10:47 AM, Greg Brown wrote:
>
>> All,
>>
>> Currently, Pivot allows a caller to disable individual items in
>> list, table, and tree views via index (or path, in the tree case).
>> This works, but does require some effort on the part of the caller,
>> since the caller needs to know which indexes map to the items they
>> want disabled.
>>
>> I'd like to propose what I think is a better solution: what if we
>> instead allow the caller to set a "disabled item filter"? This would
>> basically amount to an implementation of some interface such as:
>>
>> package org.apache.pivot.util;
>> public interface Filter {
>> 	public boolean accept(Object object);
>> }
>>
>> or possibly:
>>
>> package org.apache.pivot.util;
>> public interface Filter<T> {
>> 	public boolean accept(T t);
>> }
>>
>> It would certainly simplify the code in TreeView, TableView, and
>> ListView, since we'd no longer need to maintain the list of disabled
>> indexes. It is also more efficient, for the same reason. Finally, it
>> is more flexible, since any items matching the filter would be
>> automatically disabled - the caller would not need to manually
>> update the disabled index list as new items were added.
>>
>> The downside is that, if the caller does actually want to disable
>> items by index, it would be difficult (or impossible) do. We could
>> add an index or path to the accept() method, but that seems like
>> overkill. I guess the question is - what use case are we addressing
>> with disabled items? Is a caller more likely to want to disable
>> items by nature or by index? I'd guess the former, but I'm not 100%
>> sure.
>>
>> Please let me know what you think.
>>
>> Thanks,
>> Greg
>>
>
>

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