Class: ValueModel

• Inheritance
• Description
• Class protocol
  • instance creation
  • queries
• Instance protocol
  • accessing
  • converting
  • inspecting
  • misc
  • queries
  • testing

Inheritance:

   Object
   |
   +--Model
      |
      +--ValueModel
         |
         +--BlockValue
         |
         +--IndirectValue
         |
         +--PluggableAdaptor
         |
         +--ProtocolAdaptor
         |
         +--ValueHolder

Package:

stx:libview2

Category:

Interface-Support-Models

Version:

rev: 1.41 date: 2023/01/06 10:42:44

user: cg

file: ValueModel.st directory: libview2

module: stx stc-classLibrary: libview2

Description:

abstract superclass for ValueHolders and Adaptors.
It does not itself know how and where the value is stored,
but knows about interested objects (which get informed, whenever
the value changes) and keeps track if the value was ever accepted.

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.

subclasses must redefine: #setValue: and #value
(and optionally redefine #value:)

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:

 new

(comment from inherited method)
return an instance of myself without indexed variables

 newWithDependent: aDependent

ValueHolder newWithDependent:[self halt].

 isAbstract

Return if this class is an abstract class.
True is returned here for myself only; false for subclasses.
Abstract subclasses must redefine this again.

Instance protocol:

 setValue: newValue

physically set my value, without change notifications

** This method must be redefined in concrete classes (subclassResponsibility) **

 triggerValue: newValue

set my value & send change notifications to my dependents.
Send the change message even if the value didn't change.

 value

return my value

** This method must be redefined in concrete classes (subclassResponsibility) **

 value: newValue

set my value & send change notifications to my dependents
if it changed.

 value: newValue withoutNotifying: someOne

like #value, but temporarily retract all interests for someOne
(i.e. the value-change will NOT directly send ANY change notification
to someOne; we cannot guarantee indirect notifications, though.)
Useful if someone is itself depending on the receiver,
and wants to avoid recursive update notifications.

 asValue

return the receiver - it is already a valueHolder

 compute: aBlock

return a BlockValue on the receiver, which computes aBlock

 inspectorValueListIconFor: anInspector
( an extension from the stx:libtool package )

returns the icon to be shown alongside the value list of an inspector

 decrement

decrement my value

 increment

increment my value

 isBuffering

return true, if the receiver is buffering something.
For compatibility with BufferedValueHolder, false is returned here

 isPluggableAdaptor

 isTypeConverter

 isValueModel

return true, if the receiver is some kind of valueModel;
true returned here - redefined from Object