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Class: TriggerValue

Inheritance:

   Object
   |
   +--Model
      |
      +--ValueModel
         |
         +--ValueHolder
            |
            +--TriggerValue
Package:
stx:libview2
Category:
Interface-Support-Models
Version:
rev: 1.10 date: 1998/07/28 09:54:04
user: cg
file: TriggerValue.st directory: libview2
module: stx stc-classLibrary: libview2
Author:
Claus Gittinger

Description:


a triggerValue sends updates on every store of a value, even if the same
value is stored again.
It can be used as a triggerChannel of a bufferedValueHolder.

(however, in this specific use, you can also use normal ValueHolder,
 and set it value to nil before setting it to the actual trigger value)

Instance protocol:

accessing
o  value: anObject
redefined to send change notifications on every store,
even if the same value is stored again.

Examples:


buffered editing with a TriggerValue 


    |firstName lastName trigger dialog|

    firstName :=  'foo' asValue.
    lastName := 'bar' asValue.
    trigger := TriggerValue new.

    dialog := Dialog new.
    (dialog addTextLabel:'Name:') layout:#left.
    (dialog addInputFieldOn:(BufferedValueHolder
                                subject:firstName
                                triggerChannel:trigger)) immediateAccept:true.
    dialog addVerticalSpace.
    (dialog addTextLabel:'Address:') layout:#left.
    (dialog addInputFieldOn:(BufferedValueHolder
                                subject:lastName
                                triggerChannel:trigger)) immediateAccept:true.

    dialog addAbortButton; 
           addButton:(Button new 
                            label:'undo'; 
                            action:[trigger value:false]);
           addOkButton.

    dialog okAction:[trigger value:true].
    dialog open.

    Transcript show:firstName value; show:' '; showCR:lastName value

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