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

[Johan Brichau]

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 <marianopeck at gmail.com> 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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