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Re: Handling ui feedback loops

by Andreas Raab :: Rate this Message:

> Whats the proper pattern for this use of tweak fields and input fields?

You'll have to guard manually, e.g., instead of either

MyInputField>>onModelValueChanged
<on: valueChanged in: model>
self value := model value asString.

MyInputField>>onValueChanged
<on: valueChanged>
model value := Number readFrom: self value.

(which may loop) use either one of:

MyInputField>>onModelValueChanged
<on: valueChanged in: model>
newValue := model value asString.
newValue = value ifFalse:[
self value := newValue.
].

MyInputField>>onValueChanged
<on: valueChanged>
newValue := Number readFrom: self value.
newValue = model value ifFalse:[
model value := newValue.
].

Cheers,
- Andreas

Steven W. Riggins wrote:

> I have a input field and when I change the value of the tweak field, its
> mirrored into the field. I also use this field as a input field, so I
> want to know when the value changed, and update my model. Problem is, I
> set the field, I get a changed event, I convert the field string gto a
> number, set my model, which updates the field, and around and around I go.
>
> propertyValueAt: key put: newValue with: changeEvent
> "Store the value of my property at key"
> | oldValue |
> myProperties ifNil:[myProperties := IdentityDictionary new].
> oldValue := myProperties atProperty: key put: newValue.
> oldValue == newValue ifTrue:[^newValue].
> self signalChanged: changeEvent from: oldValue to: newValue.
> ^newValue
>
> Does ==, which fails because '123' == (123 asString) fails.
>
> WHats the proper pattern for this use of tweak fields and input fields?
> _______________________________________________
> Tweak mailing list
> Tweak@...
> http://impara.de/mailman/listinfo/tweak
>
>

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