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Mark Mayfield wrote to the Squeak mailing list on Thu, 19 Aug 1999:
Being someone that is a purest at heart when it comes to separating
business logic, i.e. the model, from its interface, i.e. a view and
controller, here is an alternative to Tim's example. It's a little
more work, but it keeps the LedMorph more of an "interface" object
by making it pluggable. The counter object is a model object, and the counting
application is a cooridnator object in that it creates the counter and pluggable led morph objects and connects them up.
It's not the best code in the world, but it gets the point across.
He also wrote on Monday, 16 Aug 1999
To me a morph is a combination of a view and a controller. I still
create separate model objects that have morphs as dependents.
The three classes
The code:
Select the code, copy it and paste it into a new Workspace. Select it and file it in. Tested with Squeak version 2.7 and 2.8.
For version 3.0 change the instantiation of the AlignmentMorphs in the method openAsMorph in the class 'CounterApplication' as explained under the second approach. (#listDirection: instead of #orientation: ). The code is in the class category 'counting'. You start the application by evaluating CounterApplication openAsMorph.
Model subclass: #Counter
instanceVariableNames: 'currentValue '
classVariableNames: ''
poolDictionaries: ''
category: 'Counting'!
!Counter methodsFor: 'initialize-release' stamp: 'mlm 8/14/1999
09:30'!
initialize
currentValue _ 0.! !
!Counter methodsFor: 'accessing' stamp: 'mlm 8/14/1999 09:29'!
currentValue
^ currentValue! !
!Counter methodsFor: 'accessing' stamp: 'mlm 8/14/1999 09:29'!
currentValue: anObject
currentValue _ anObject.
self changed: #currentValue! !
!Counter methodsFor: 'counting' stamp: 'mlm 8/14/1999 09:31'!
clear
self currentValue: 0! !
!Counter methodsFor: 'counting' stamp: 'mlm 8/14/1999 09:32'!
decrement
self currentValue: self currentValue - 1! !
!Counter methodsFor: 'counting' stamp: 'mlm 8/14/1999 09:32'!
increment
self currentValue: self currentValue + 1! !
"– – – – – – – – – – – – – – – – – – "!
Counter class
instanceVariableNames: ''!
!Counter class methodsFor: 'instance creation' stamp: 'mlm 8/14/1999
09:34'!
new
^ super new initialize! !
Model subclass: #CounterApplication
instanceVariableNames: 'counter frame display controls '
classVariableNames: ''
poolDictionaries: ''
category: 'Counting'!
!CounterApplication methodsFor: 'user interface' stamp: 'mlm 8/16/1999
13:25'!
openAsMorph
"create a model object"
counter _ Counter new.
"this is going to be the box containing our panel"
frame := AlignmentMorph new
orientation: #vertical.
"create a 4-digit LED display to contain the count"
display := (PluggableLedMorph on: counter value: #currentValue)
digits: 4;
extent: (410@150).
"make the display a dependent of the model"
counter addDependent: display.
"we want our buttons arranged in a horizontal row"
controls := AlignmentMorph new
orientation: #horizontal.
"add a quit button"
controls addMorph:
(SimpleButtonMorph new
target: frame;
label: 'quit';
actionSelector: #delete).
"add an increment button"
controls addMorph:
(SimpleButtonMorph new
target: counter;
label: 'inc';
actionSelector: #increment).
"add a decrement button"
controls addMorph:
(SimpleButtonMorph new
target: counter;
label: 'dec';
actionSelector: #decrement).
"add a clear button"
controls addMorph:
(SimpleButtonMorph new
target: counter;
label: 'clear';
actionSelector: #clear).
"add the controls and display to our panel"
frame addMorph: controls.
frame addMorph: display.
"start playing with it!!"
frame openInWorld! !
"– – – – – – – – – – – – – – – – – – "!
CounterApplication class
instanceVariableNames: ''!
!CounterApplication class methodsFor: 'instance creation' stamp:
'mlm 8/16/1999 13:25'!
openAsMorph
"CounterApplication openAsMorph"
^self new openAsMorph! !
LedMorph subclass: #PluggableLedMorph
instanceVariableNames: 'getValueSelector model '
classVariableNames: ''
poolDictionaries: ''
category: 'Counting'!
!PluggableLedMorph methodsFor: 'initialize-release' stamp: 'mlm
8/16/1999 13:05'!
on: anObject value: aSelector
self model: anObject.
self getValueSelector: aSelector! !
!PluggableLedMorph methodsFor: 'accessing' stamp: 'mlm 8/16/1999
13:03'!
getValueSelector
^ getValueSelector! !
!PluggableLedMorph methodsFor: 'accessing' stamp: 'mlm 8/16/1999
13:05'!
getValueSelector: aSelector
getValueSelector _ aSelector! !
!PluggableLedMorph methodsFor: 'accessing' stamp: 'mlm 8/16/1999
13:02'!
model
^ model! !
!PluggableLedMorph methodsFor: 'accessing' stamp: 'mlm 8/16/1999
13:05'!
model: aModel
model _ aModel! !
!PluggableLedMorph methodsFor: 'updating' stamp: 'mlm 8/16/1999
13:06'!
update: aSymbol
aSymbol == getValueSelector
ifTrue: [^ self value: (self model perform: self getValueSelector)]! !
"– – – – – – – – – – – – – – – – – –"
PluggableLedMorph class
instanceVariableNames: ''!
!PluggableLedMorph class methodsFor: 'instance creation' stamp:
'mlm 8/16/1999 12:59'!
on: anObject value: aSelector
^ self new on: anObject value: aSelector! !