"
COPYRIGHT (c) 2003 by eXept Software AG
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.
"
"{ Package: 'stx:libbasic2' }"
"{ NameSpace: Smalltalk }"
CacheDictionary subclass:#CacheDictionaryWithFactory
instanceVariableNames:'factoryBlock'
classVariableNames:''
poolDictionaries:''
category:'Collections-Unordered'
!
!CacheDictionaryWithFactory class methodsFor:'documentation'!
copyright
"
COPYRIGHT (c) 2003 by eXept Software AG
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.
"
!
documentation
"
like a Dictionary, but does not grow beyond a given max. size
(i.e. only keeps size items),
It can be used as a cache, for keeping recently used objects alive.
Must be created with an initial (=maximal) size.
In addition to the normal CacheDictionary,
this also keeps a factoryBlock to automatically compute missing elements.
[author:]
Claus Gittinger (cg@alan)
[see also:]
CacheDictionary
Dictionary
"
!
examples
"
caches reverse strings (stupid usage)
[exBegin]
|c|
c := CacheDictionaryWithFactory
new:100 factory:[:key | key reversed].
c at:'hello'.
c at:'hello'.
1 to:1000 do:[:i | c at:i printString].
c at:'hello'.
[exEnd]
Test: should halt (compute 'hello') only twice.
[exBegin]
|c numHalts|
numHalts := 0.
c := CacheDictionaryWithFactory
new:100 factory:[:key | key = 'hello' ifTrue:[numHalts := numHalts + 1]. key reversed].
c at:'hello'.
c at:'hello'.
1 to:1000 do:[:i | c at:i printString].
c at:'hello'.
self assert:( numHalts == 2 ).
[exEnd]
"
! !
!CacheDictionaryWithFactory class methodsFor:'instance creation'!
new:cacheSize factory:aBlock
^ (self new:cacheSize) factory:aBlock
! !
!CacheDictionaryWithFactory methodsFor:'accessing'!
at:key
^ super at:key ifAbsentPut:[factoryBlock value:key]
! !
!CacheDictionaryWithFactory methodsFor:'initialization'!
factory:aBlock
factoryBlock := aBlock
! !
!CacheDictionaryWithFactory class methodsFor:'documentation'!
version
^ '$Header$'
! !