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How childrenBlock: in TreeModel works

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chrismihaylyk

How childrenBlock: in TreeModel works

Hi!

Could anyone explain me how works childrenBlock: method from TreeModel? step-by-step.
What data it operates? How makes a result?

Thanks a lot? Khrystyna.

Peter Uhnak

Re: How childrenBlock: in TreeModel works

Hi,

I wanted to point you to the new Spec book ( http://files.pharo.org/books-pdfs/spec/2017-01-23-SpecBooklet.pdf ), but apprently it's not there.

Many Spec widgets have examples accompanying them, so always check class side (not for all though). For TreeModel you can see couple there - good for playing around; e.g.

exampleWithNoSpecifiedNodes
"self exampleWithNoSpecifiedNodes"
TreeModel new
roots: (1 to: 5);
childrenBlock: [ :item | 1+item to: 5+item ];
openWithSpec

You specify the initial data (root nodes) via the `roots:` message.
The `childrenBlock:` then specifies how one would retrieve data given a particular node; note that this applies to _any node_, not just the root ones; so you can have potentially infinitely deep trees.

A more complex example could be this (this is awful code for demonstration only ;):

TreeModel new
roots: {#parent. #childless. 20. #root -> #(a b c)};
childrenBlock: [ :item |
item isSymbol ifTrue: [
item = #parent
ifTrue: [ #(child1 child2) ]
ifFalse: [ #() ]
] ifFalse: [
item isNumber
ifTrue: [ {item + 2. item ** 2} ]
ifFalse: [ "association" item value ]
]
];
openWithSpec

Peter

On Sat, Apr 01, 2017 at 06:49:41AM -0700, chrismihaylyk wrote:

> Hi!
>
> Could anyone explain me how works childrenBlock: method from TreeModel?
> step-by-step.
> What data it operates? How makes a result?
>
> Thanks a lot? Khrystyna.
>
>
>
>
>
> --
> View this message in context: http://forum.world.st/How-childrenBlock-in-TreeModel-works-tp4940884.html
> Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.
>

chrismihaylyk

Re: How childrenBlock: in TreeModel works

Now I understand. Thank you very much! =)

2017-04-01 17:48 GMT+03:00 Peter Uhnak <[hidden email]>:

Hi,

I wanted to point you to the new Spec book ( http://files.pharo.org/books-pdfs/spec/2017-01-23-SpecBooklet.pdf ), but apprently it's not there.

Many Spec widgets have examples accompanying them, so always check class side (not for all though). For TreeModel you can see couple there - good for playing around; e.g.

exampleWithNoSpecifiedNodes
"self exampleWithNoSpecifiedNodes"
TreeModel new
roots: (1 to: 5);
childrenBlock: [ :item | 1+item to: 5+item ];
openWithSpec

You specify the initial data (root nodes) via the `roots:` message.
The `childrenBlock:` then specifies how one would retrieve data given a particular node; note that this applies to _any node_, not just the root ones; so you can have potentially infinitely deep trees.

A more complex example could be this (this is awful code for demonstration only ;):

TreeModel new
roots: {#parent. #childless. 20. #root -> #(a b c)};
childrenBlock: [ :item |
item isSymbol ifTrue: [
item = #parent
ifTrue: [ #(child1 child2) ]
ifFalse: [ #() ]
] ifFalse: [
item isNumber
ifTrue: [ {item + 2. item ** 2} ]
ifFalse: [ "association" item value ]
]
];
openWithSpec

Peter

On Sat, Apr 01, 2017 at 06:49:41AM -0700, chrismihaylyk wrote:
> Hi!
>
> Could anyone explain me how works childrenBlock: method from TreeModel?
> step-by-step.
> What data it operates? How makes a result?
>
> Thanks a lot? Khrystyna.
>
>
>
>
>
> --
> View this message in context: http://forum.world.st/How-childrenBlock-in-TreeModel-works-tp4940884.html
> Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.
>

chrismihaylyk

Re: How childrenBlock: in TreeModel works

Hello!

Could anyone help me, please?

I have faced with a problem of TreeModel childrenBlock: for more complex build in structure.

For example, I have anOrderedCollection of Dictionary, and in each dictionary, there are exist associations, which values are anArray(aDictionary, aDictionary ...).

I need to make drop downs for all of these entire levels of arrays and dictionaries.
For first level I made it:

collectionsList
ifNil: [ ^ nil ]
ifNotNil: [ collectionsList hasChildrenBlock: [ :item | item isMyDictionary. ].
collectionsList
childrenBlock: [ :item | item associations
collect: [ :assoc |
assoc key asString , ' -> ' , assoc value asString. ] ] ]

MyDictionaly is the class, inherited from Dictionary, just to override method printOn:

At the first picture, it's how it looks like, how I made it.
At the second - how I expect it to be (taken from Inspector window).

Thanks a lot!

Peter Uhnak

Re: How childrenBlock: in TreeModel works

I guess something like this could work...

```
d := {
Dictionary
with: #n -> 'whatever'
with: #d -> {
Dictionary with: #a -> #AA with: #b -> #BB.
Dictionary with: #c -> #CC with: #d -> #DD
}.

Dictionary
with: #n -> 'wherever'
with: #d -> {
Dictionary
with: #a -> #AA
with: #b -> #BB.
Dictionary with: #c -> #CC with: #d -> #DD
}.
}.

TreeModel new
roots: d;
childrenBlock: [ :item |
item isDictionary
ifTrue: [
item associations flatCollect: [ :pair |
pair value isArray
ifTrue: [ pair value ]
ifFalse: [ {pair} ].
]
]
ifFalse: [ #() ]
];
openWithSpec
```

but forcing this much behavior is a bad practice... because it's hard to read, hard to understand, and hard to test.

So I suggest using custom classes as nodes (so each node can simply tell what its children are), and then delegate the retrieval... you could also add extension methods to the respective classes' protocols to acheive the same...

TreeModel new
childrenBlock: [ :item |
item children
];
displayBlock: [ :item |
item name
]

Peter

On Mon, Apr 17, 2017 at 09:12:47AM -0700, chrismihaylyk wrote:

> Hello!
>
> Could anyone help me, please?
>
> I have faced with a problem of TreeModel childrenBlock: for more complex
> build in structure.
>
> For example, I have anOrderedCollection of Dictionary, and in each
> dictionary, there are exist associations, which values are
> anArray(aDictionary, aDictionary ...).
>
> I need to make drop downs for all of these entire levels of arrays and
> dictionaries.
> For first level I made it:
>
> collectionsList
> ifNil: [ ^ nil ]
> ifNotNil: [ collectionsList hasChildrenBlock: [ :item | item
> isMyDictionary. ].
> collectionsList
> childrenBlock: [ :item | item associations
> collect: [ :assoc |
> assoc key asString , ' -> ' , assoc value asString. ] ] ]
>
> MyDictionaly is the class, inherited from Dictionary, just to override
> method printOn:
>
> At the first picture, it's how it looks like, how I made it.
> At the second - how I expect it to be (taken from Inspector window).
>
> Thanks a lot!
> <http://forum.world.st/file/n4942409/before.jpg>
> <http://forum.world.st/file/n4942409/after.jpg>
>
>
>
>
> --
> View this message in context: http://forum.world.st/How-childrenBlock-in-TreeModel-works-tp4940884p4942409.html
> Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.
>