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
            |
            +--ValueHolderWithRememberedPreviousValue
            |
            +--ValueHolderWithWeakDependents

Package:

stx:libview2

Category:

Interface-Support-Models

Version:

rev: 1.27 date: 2023/06/10 07:39:20

user: cg

file: ValueHolder.st directory: libview2

module: stx stc-classLibrary: libview2

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.

copyright
COPYRIGHT (c) 1995 by Claus Gittinger
             All Rights Reserved

This software is furnished under a license and may be used
only in accordance with the terms of that license and with the
inclusion of the above copyright notice.   This software may not
be provided or otherwise made available to, or used by, any
other person.  No title to or ownership of the software is
hereby transferred.

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

 newWithDependent: aDependent

(comment from inherited method)
ValueHolder newWithDependent:[self halt].

 with: anObject

return a new ValueHolder holding anObject as initial value

 with: anObject onChangeSend: selector to: stakeHolder

return a new ValueHolder holding anObject as initial value

Instance protocol:

 setDependents: aCollectionOrDependentOrNil

private for initialization only

 setValue: anObject

set my value without notification.

 value

return my value

 displayOn: aGCOrStream

Compatibility
append a printed desription on some stream (Dolphin, Squeak)
OR:
display the receiver in a graphicsContext at 0@0 (ST80).
This method allows for any object to be displayed in some view
(although the fallBack is to display its printString ...)

 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
    ]