"Flyweight"

"Ez a példa egy image osztályt mutat be melytől le lehet kérni a Save es a Help ikont. A terminta ott valósul meg hogy ezeknek az ikonoknak csak egy példanyukat tároljuk el egy pool-ban."


Image class>>initialize 
"Set the class' initial state." 
"[Image initialize]" 
Smalltalk 
at: #ImagePool 
put: IdentityDictionary new. 
^self


Image class>>release 
"Prepare the class to be deleted." 
"[Image release]" 
Smalltalk at: #ImagePool put: nil. 
Smalltalk removeKey: #ImagePool. 
^self


Image class>>imageCache 
"Return the Image caching dictionary." 
^ImagePool


Image class>>createSaveIcon 
"Create and return the Image for the Save icon." 
^MainMenUI createSaveIcon


Image class>>helpIcon 
"Return the Image for the Help icon." 
| cacheDictionary | 
cacheDictionary := self imageCache. 
^cacheDictionary 
at: #help 
ifAbsent: 
[cacheDictionary 
at: #help 
put: self createHelpIcon]


Image class>>saveIcon 
"Return the Image for the Save icon." 
| cacheDictionary | 
cacheDictionary := self imageCache. 
^cacheDictionary 
at: #save 
ifAbsent: 
[cacheDictionary 
at: #save 
put: self createSaveIcon]


Object subclass: #ImageFactory 
instanceVariableNames: 'imagePool ' 
classVariableNames: 'Singleton ' 
poolDictionaries: ''


ImageFactory class>>initialize 
"Set the class' initial state." 
"[ImageFactory initialize]" 
Singleton := self new. 
^self


ImageFactory class>>release 
"Prepare the class to be deleted." 
"[ImageFactory release]" 
Singleton := nil. 
^self


ImageFactory class>>default 
"Return the class' primary instance." 
^Singleton


ImageFactory>>initialize 
"Set the instance's initial state." 
imagePool := IdentityDictionary new. 
^self


ImageFactory class>>new 
"Create and return an instance of the class." 
^self basicNew initialize