Class: ValueHolder

• Inheritance
• Description
• Class protocol
  • instance creation
• Instance protocol
  • accessing
  • printing & storing
• Examples

Inheritance:

   Object
   |
   +--Model
      |
      +--ValueModel
         |
         +--ValueHolder
            |
            +--BooleanValueHolder
            |
            +--BufferedValueHolder
            |
            +--RadioButtonGroup
            |
            +--RangeAdaptor
            |
            +--SelectionInList
            |
            +--TriggerValue
            |
            +--ValueHolderWithWeakDependents

Package:

stx:libview2

Category:

Interface-Support-Models

Version:

rev: 1.19 date: 2009/10/22 19:09:13

user: cg

file: ValueHolder.st directory: libview2

module: stx stc-classLibrary: libview2

Author:

Claus Gittinger

Description:

a valueHolder can be used as a model for editFields, buttons etc.
It stores some value internally, and sends update messages to its
dependents when changed.

Notice: 
    this class was implemented using protocol information
    from alpha testers - it may not be complete or compatible to
    the corresponding ST-80 class. 
    If you encounter any incompatibilities, please forward a note 
    describing the incompatibility verbal (i.e. no code) to the ST/X team.

Class protocol:

 newBoolean

return a new ValueHolder holding false as initial value

 newFraction

return a new ValueHolder holding 0.0 as initial value.
The name is somewhat missleading - actually it should be called newFloat.

 newNumber

return a new ValueHolder holding 0 as initial value

 newString

return a new ValueHolder holding an empty string as initial value

 with: anObject

return a new ValueHolder holding anObject as initial value

Instance protocol:

 setValue: anObject

set my value without notification.

 value

return my value

 displayString

return a string for display in inspectors etc.

 printOn: aStream

return a string for display in inspectors etc.

Examples:

    |firstName lastName dialog|

    firstName := ValueHolder newString.
    lastName := ValueHolder newString.

    dialog := Dialog new.
    (dialog addTextLabel:'Name:') adjust:#left.
    dialog addInputFieldOn:firstName.
    dialog addVerticalSpace.
    (dialog addTextLabel:'Address:') adjust:#left.
    dialog addInputFieldOn:lastName.

    dialog addAbortButton; addOkButton.

    dialog open.
    dialog accepted ifTrue:[
        Transcript show:firstName value; show:' '; showCR:lastName value
    ]