How to use trees with OrderedCollections etc

Hi all,

one more stupid question. I've been building a UI mockup happily
quoting the sample that reads

      tree := (Iliad.Tree new)
                 item: Object;
                 childrenBlock: [:class | class subclasses];
                 contentsBlock: [:e :class | e text: class name]

it works perfectly. Then I spent quite a long time getting stuff out
of PG, decoding the XML to make it in objects and I finally have
something I can use. It's anOrderedCollection of symbols (uuids,
actually) that I will later turn into properly localized objects
depending on what language the users has chosen.

It looks like:
An instance of OrderedCollection
  firstIndex: 8
  lastIndex: 16
  contents: [
    [1]: #'1aa75482-4e61-11de-a0cb-e7dd9793c483'
    [2]: #'d39605ea-7929-11de-9575-839884ebf70c'
    [3]: #'d3973a46-7929-11de-b337-4fd741cce41e'
    [4]: #'d3984bca-7929-11de-a337-bb66b2b01db0'
    [5]: #'d39968f2-7929-11de-bb33-83f0278053f7'
    [6]: #'d39a6ebe-7929-11de-8ea2-5bd631a2b97f'
    [7]: #'d39c66b0-7929-11de-9f31-1fcdae4e56a0'
    [8]: #'d39d7e24-7929-11de-8f93-733ef5534d68'
    [9]: #'d39e76a8-7929-11de-ad21-73754236fffa'
  ]

Now, my idea was to move up the mock a bit by showing the uuids. Note
that in this case it's not really a tree, yet. It will probably get to
be one, but even if it doesn't I'd rather have the same widget for all
lists, so users do not have to learn too much stuff before they can
use the app.

Now, I probably need some sleep badly, but for the life of me I cannot
figure out how to pass this collection to the tree and have it shown
as a simple list. So while I wait for someone to shed light on my
dumbness I'll go on with other parts of the code.

Berto


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Hi,

Since it's a tree widget, it expects an item of the tree to know its
children. This part is done in #childrenBlock:

The thing is that you're OrderedCollection is not a tree, so objects of
the collection don't have  children. So I don't think a tree widget is
what you need, I would rather use a simple list in your case.

Is there a reason why you want to use a tree widget?

Cheers!

Nico



Le mardi 10 novembre 2009 à 08:46 +0200, Bèrto ëd Sèra a écrit :
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Le mardi 10 novembre 2009 à 08:46 +0200, Bèrto ëd Sèra a écrit :
> Note
> that in this case it's not really a tree, yet. It will probably get to
> be one, but even if it doesn't I'd rather have the same widget for all
> lists, so users do not have to learn too much stuff before they can
> use the app.

But what's the point of using a tree widget to represent a list? Also, I
think you can make a list and a tree feel the same with some css, list
item won't be expandable, that's all.

Nico

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On Tue, 10 Nov 2009 08:46:10 +0200
Bèrto ëd Sèra <[hidden email]> wrote:

> Hi all,
>
> one more stupid question. I've been building a UI mockup happily
> quoting the sample that reads
>
>       tree := (Iliad.Tree new)
>                  item: Object;
>                  childrenBlock: [:class | class subclasses];
>                  contentsBlock: [:e :class | e text: class name]

I guess the main problem is that the above combination of Object and
#subclasses leads to a tree of objects implementing the message #subclasses,
while you have a collection (responding to #contents) and symbols (not
responding to #contents).

One way to get around this is to wrap your different objects into a thin
decorator providing a common interface, so that the following would work:

tree := (Iliad.Tree new)
           item: myTreeViewableCollectionOfLocalizableSymbols
           childrenBlock: [:item | item children ]
           contentsBlock: [:e :item | e text: item displayString ]

I apologize for that looong name :-)

Object subclass: TreeNodeHolder [
  | model getter |
  class [
    on: anObject getter: aBlock [
      ^ self basicNew model: anObject; getter: aBlock; yourself
    ]
  ]
  children [ ^ getter value: model ]
]

treeModel := TreeNodeHolder
               on: myTVCOLS
               getter: [:coll | coll collect: [:elt |
                          TreeNodeHolder on: elt getter: [:sym | OrderedCollection new ]
                       ].
tree := (Iliad.Tree new)
           item: treeModel
           childrenBlock: [:item | item children ]
           contentsBlock: [:e :item | e text: item displayString ]

Mind you, this snippet was written with dangerously low blood sugar levels,
so beware :-)

You can also avoid a lot of the uglyness if your application classes implement
a consistent interface for this purpose from the start.

HTH
s.


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