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"
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COPYRIGHT (c) 1992 by Claus Gittinger
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All Rights Reserved
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This software is furnished under a license and may be used
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only in accordance with the terms of that license and with the
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inclusion of the above copyright notice. This software may not
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be provided or otherwise made available to, or used by, any
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other person. No title to or ownership of the software is
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hereby transferred.
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"
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Object subclass:#Model
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instanceVariableNames:'dependents'
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classVariableNames:''
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poolDictionaries:''
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category:'Interface-Support-Models'
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!
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!Model class methodsFor:'documentation'!
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copyright
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"
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COPYRIGHT (c) 1992 by Claus Gittinger
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All Rights Reserved
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This software is furnished under a license and may be used
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only in accordance with the terms of that license and with the
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inclusion of the above copyright notice. This software may not
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be provided or otherwise made available to, or used by, any
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other person. No title to or ownership of the software is
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hereby transferred.
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"
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!
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documentation
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"
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Models are things that are presented in views. Instances keep track of
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which views are dependent of them and inform them of any changes.
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Actually the Model class is not really needed; since the dependency
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mechanism is inherited by Object, you can take any object as a model.
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However, instances of Model (and subclasses) keep the dependents locally
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in an instance variable; thus speeding up access a bit.
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Instance variables:
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dependents Collection those objects which depend on me.
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To save some storage, the dependent is
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kept directly here, IFF there os only one.
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Otherwise, a collection of dependents is
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held here.
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"
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!
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version
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^ '$Header: /cvs/stx/stx/libview2/Model.st,v 1.16 1995-11-23 10:42:21 cg Exp $'
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! !
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!Model methodsFor:'copying'!
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postCopy
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"release dependents after copying"
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self dependents:nil
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! !
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!Model methodsFor:'dependents access'!
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addDependent:anObject
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"make the argument, anObject be a dependent of the receiver"
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|deps|
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deps := dependents.
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deps isNil ifTrue:[
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dependents := anObject
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] ifFalse:[
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(deps isMemberOf:IdentitySet) ifTrue:[
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deps add:anObject
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] ifFalse:[
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dependents := IdentitySet with:dependents with:anObject
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]
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]
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!
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dependents
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"return a Collection of dependents - nil if there is none"
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^ dependents
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!
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dependents:aCollection
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"set the collection of dependents"
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dependents := aCollection
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!
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dependentsDo:aBlock
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"evaluate aBlock for all of my dependents"
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|deps|
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deps := dependents.
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deps notNil ifTrue:[
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(deps isMemberOf:IdentitySet) ifTrue:[
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deps do:aBlock
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] ifFalse:[
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aBlock value:deps
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]
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]
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!
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release
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dependents := nil
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!
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removeDependent:anObject
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"make the argument, anObject be independent of the receiver"
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|deps sz|
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deps := dependents.
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deps notNil ifTrue:[
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(deps isMemberOf:IdentitySet) ifTrue:[
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deps remove:anObject ifAbsent:[].
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(sz := deps size) == 1 ifTrue:[
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dependents := deps first
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] ifFalse:[
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(sz == 0) ifTrue:[
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dependents := nil
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]
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]
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] ifFalse:[
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dependents := nil
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]
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]
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! !
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!Model methodsFor:'drawing'!
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displayOn:aGraphicsContext
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"display myself in aGraphicsContext"
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^ self subclassResponsibility
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!
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displayOn:aGraphicsContext clippingBox:aRectangle
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"display a part of me in aGraphicsContext"
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^ self subclassResponsibility
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! !
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