[Glass] Problem assigning to temp vars from Seaside callbacks?

Hey Mariano,

If you want to transfer values between callbacks (closures) in Seaside on Gemstone, you need to put the value in a valueholder object instead of assigning to method temporaries. Otherwise, you experience exactly what you see. That means, for example:

| valueholder|
valueholder := ValueHolder new.

html jQuery ajax
        callback: [:v | valueholder value: v];
        script: [:s | self doSomethingWith: valueholder value]

You can use anything you like as a valueholder: Association, Array, Set, ... whatever. As long as you are not directly assigning to the temporary var.
There is also code demonstrating this in the JQueryUI Autocomplete code of Seaside (gemstone version) [2].

I referred to that issue in this mail [1] but it was a bit condensed I guess.

cheers
Johan

[1] http://forum.world.st/Glass-Basic-questions-regarding-GemBuilder-for-Smalltalk-GemTools-and-tODE-tp4711463p4711987.html
[2] https://github.com/glassdb/Seaside31/blob/gemstone3.1/repository/JQuery-UI.package/JQAutocomplete.class/instance/search.labels.callback..st

On 27 Jan 2014, at 22:10, Mariano Martinez Peck <[hidden email]> wrote:

> Hi guys,
>
> I am starting to see strange problems that happen only in GemStone but work correctly in Pharo.
>
> I have a menu action that looks like this:
>
>
> (aWebAppBrowser actionType new
>               context: #contextMenu;
>               argumentTypes:
>                               {Object.
>                                       Collection.
>                                       (aWebAppBrowser class)};
>               label: 'SIXX Import and Replace DB';
>               block: [ :cls :collection :app |
>                                       | list |
>                                       (app activeModelReport isKindOf: MAReport)
>                                               ifTrue: [ | filenameForm filename |
>                                                       list := app objectsForActions.  "filtered and sorted"
>                                                       filenameForm := MyRenderedBlockFormDialog new.
>                                                       filenameForm
>                                                               buttonsAndCallbacksList:
>                                                                       {(#import -> [ filenameForm answer: true ]).
>                                                                       (#cancel -> [ filenameForm answer: false ])};
>                                                               renderingBlock: [ :html |
>                                                                       html text: 'Import filename prefix'.
>                                                                       html textInput
>                                                                               size: 100;
>                                                                               callback: [ :value | self halt. filename := value trimBoth ];
>                                                                               value: 'filename_here' ];
>                                                               addForm.
>                                                       (app call: filenameForm)
>                                                               ifTrue: [
>                                                                       self halt.
>
>                                                               ]
>                                                       ]]
>
>
> That action has the closure which is compiled once at the beginning of the app and then valued whenever clicked. Now...that closure creates an instance of MyRenderedBlockFormDialog which has a simple input for a filename. When I click on "import" the callback of the text input is invoked correctly. Soo....'filename' temp receives the value correctly. However, after the call to such a component (app call: filenameForm), (the "self halt" inside the ifTrue)... the temp var 'filename' has a nil!!!!   Any ideas why I get a nil here instead of the real value?
> Same code and same test in Pharo does work correctly.
>
> Thanks in advance,
>
> --
> Mariano
> http://marianopeck.wordpress.com

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