ProtocolAdaptor subclass:#AspectAdaptor 

	 instanceVariableNames:'myAspect getMsg putMsg'

	 classVariableNames:''

	 poolDictionaries:''

!

!AspectAdaptor class methodsFor:'documentation'!

copyright

"

 COPYRIGHT (c) 1995 by Claus Gittinger

 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.

"

!

version

"

"

!

documentation

"

    an AspectAdaptor forwards updates and change messages

    from/to a complex model.

    Consider the case where editFields are required for the

    elements (instance variables) of a more complex model.

    Without an aspect adaptor, you needed to copy the individual

    values out-of and into multiple valueHolders.

    An aspectAdaptor makes this easier, by playing model with

    vale/value: symbols towards the editField, and forwarding changes and

    updates to/from the complex model using different aspect symbols.

    Notice: this class was implemented using protocol information

    from alpha testers and PD code - it may not be complete or compatible to

    the corresponding ST-80 class. If you encounter any incompatibilities,

    please forward a note to the ST/X team.

"

!

examples

"

    a dialog on a points x/y coordinates:

	|dialog data f|

	data := 0@0.

	dialog := DialogBox new.

	dialog addTextLabel:'x:'.

	f := dialog addInputFieldOn:(AspectAdaptor new

					subject:data; 

					accessWith:#x 

					assignWith:#x:).

	f converter:(PrintConverter new initForNumber).

	dialog addTextLabel:'y:'.

	f := dialog addInputFieldOn:(AspectAdaptor new

					subject:data; 

					forAspect:#y).

	f converter:(PrintConverter new initForNumber).

	dialog addOkButton.

	data inspect.

	dialog open.

	dialog accepted ifTrue:[

	    Transcript showCr:'data now: ' , data printString

	]

    a dialog on a four-field complex model:

	|dialog data dataModel|

	data := #('hello' 'one' 'two' 'three').

	dataModel := Plug new.

	dataModel respondTo:#field1 with:[data at:1].

	dataModel respondTo:#field2 with:[data at:2].

	dataModel respondTo:#field3 with:[data at:3].

	dataModel respondTo:#field4 with:[data at:4].

	dataModel respondTo:#field1: with:[:arg | data at:1 put:arg].

	dataModel respondTo:#field2: with:[:arg | data at:2 put:arg].

	dataModel respondTo:#field3: with:[:arg | data at:3 put:arg].

	dataModel respondTo:#field4: with:[:arg | data at:4 put:arg].

	dialog := DialogBox new.

	dialog addTextLabel:'1:'.

	dialog addInputFieldOn:(AspectAdaptor new

					subject:dataModel; 

					accessWith:#field1

					assignWith:#field1:). 

	dialog addTextLabel:'2:'.

	dialog addInputFieldOn:(AspectAdaptor new

					subject:dataModel; 

					forAspect:#field2).

	dialog addTextLabel:'3:'.

	dialog addInputFieldOn:(AspectAdaptor new

					subject:dataModel; 

					accessWith:#field3

					assignWith:#field3:

					aspect:#field3). 

	dialog addTextLabel:'4:'.

	dialog addInputFieldOn:(AspectAdaptor new

					subject:dataModel; 

					forAspect:#field4).

	dialog addOkButton.

	dataModel inspect.

	dialog open.

	dialog accepted ifTrue:[

	    Transcript showCr:'data now: ' , data printString

	]

"

! !

!AspectAdaptor class methodsFor:'instance creation'!

accessWith:getSelector assignWith:putSelector 

    ^ (self new) accessWith:getSelector assignWith:putSelector

! !

!AspectAdaptor methodsFor:'change & update'!

update:something with:aParameter from:changedObject

    "translate an update from the model into a #value-change

     via my depenedents ..."

    ((changedObject == subject)

    or:[changedObject == subjectChannel]) ifTrue:[

	something == self forAspect ifTrue:[

	    self changed:#value

	].

	^ self

    ].

! !

!AspectAdaptor methodsFor:'accessing-value'!

value

    "translate a query for my value from my user

     into an aspect access towards my subject"

    |target|

    target := super value.

    ^ target perform:getMsg

!

setValue:newValue

    |target oldValue|

    target := super value.

    oldValue := target perform:getMsg.

    oldValue ~~ newValue ifTrue:[

	target perform:putMsg with:newValue.

    ]

!

value:newValue

    |target oldValue|

    target := super value.

    oldValue := target perform:getMsg.

    oldValue ~~ newValue ifTrue:[

	target perform:putMsg with:newValue.

	subjectSendsUpdates ifFalse:[

	    self changed:#value

	]

    ]

! !

!AspectAdaptor methodsFor:'accessing-spec'!

forAspect

    myAspect isNil ifTrue:[

	^ getMsg

    ].

    ^ myAspect

!

forAspect:aSelector

    getMsg := myAspect := aSelector.

    putMsg := (aSelector , ':') asSymbol.

!

accessWith:getSelector assignWith:putSelector

    getMsg := getSelector.

    putMsg := putSelector

!

accessWith:getSelector assignWith:putSelector aspect:aspectSymbol

    getMsg := getSelector.

    putMsg := putSelector.

    myAspect := aspectSymbol

! !