Why is Stack extending from LinkedList?
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Why is Stack extending from LinkedList?
 
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Hi list,
is there a specific reason Stack is extending from LinkedList, instead of using a LinkedList internally? To me, it seems that the protocol that LinkedList, SequenceableCollection, ... provides is not the protocol you expect from a Stack? Any thoughts on this? Kind regards, Bart -- imagination is more important than knowledge - Albert Einstein Logic will get you from A to B. Imagination will take you everywhere - Albert Einstein Learn from yesterday, live for today, hope for tomorrow. The important thing is not to stop questioning. - Albert Einstein The true sign of intelligence is not knowledge but imagination. - Albert Einstein However beautiful the strategy, you should occasionally look at the results. - Sir Winston Churchill It's not enough that we do our best; sometimes we have to do what's required. - Sir Winston Churchill _______________________________________________ Pharo-project mailing list [hidden email] http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project |
Re: Why is Stack extending from LinkedList?
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I wonder why there is the need for a stack class at all?
OrderedCollection is the class designed to do Stacks and Queues efficiently and portably, see #addFirst:, #addLast:, #first, #last, #removeFirst, #removeLast. Lukas 2010/8/26 Bart Gauquie <[hidden email]>: > Hi list, > > is there a specific reason Stack is extending from LinkedList, instead of > using a LinkedList internally? > To me, it seems that the protocol that LinkedList, SequenceableCollection, > ... provides is not the protocol you expect from a Stack? > > Any thoughts on this? > > Kind regards, > > Bart > > -- > imagination is more important than knowledge - Albert Einstein > Logic will get you from A to B. Imagination will take you everywhere - > Albert Einstein > Learn from yesterday, live for today, hope for tomorrow. The important thing > is not to stop questioning. - Albert Einstein > The true sign of intelligence is not knowledge but imagination. - Albert > Einstein > However beautiful the strategy, you should occasionally look at the results. > - Sir Winston Churchill > It's not enough that we do our best; sometimes we have to do what's > required. - Sir Winston Churchill > > _______________________________________________ > Pharo-project mailing list > [hidden email] > http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project > -- Lukas Renggli www.lukas-renggli.ch _______________________________________________ Pharo-project mailing list [hidden email] http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project |
Re: Why is Stack extending from LinkedList?
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Good thinking, remove Stack then?
On Thu, Aug 26, 2010 at 1:33 PM, Lukas Renggli <[hidden email]> wrote: I wonder why there is the need for a stack class at all? -- imagination is more important than knowledge - Albert Einstein Logic will get you from A to B. Imagination will take you everywhere - Albert Einstein Learn from yesterday, live for today, hope for tomorrow. The important thing is not to stop questioning. - Albert Einstein The true sign of intelligence is not knowledge but imagination. - Albert Einstein However beautiful the strategy, you should occasionally look at the results. - Sir Winston Churchill It's not enough that we do our best; sometimes we have to do what's required. - Sir Winston Churchill _______________________________________________ Pharo-project mailing list [hidden email] http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project |
Re: Why is Stack extending from LinkedList?
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In reply to this post by Bart Gauquie
On Thu, 26 Aug 2010, Bart Gauquie wrote:
> Hi list, > > is there a specific reason Stack is extending from LinkedList, instead of > using a LinkedList internally? > To me, it seems that the protocol that LinkedList, SequenceableCollection, > ... provides is not the protocol you expect from a Stack? > > Any thoughts on this? Originally it used encapsulation, but for some reason it was changed to use inheritance, probably for a "cleaner" system. IMHO the changes should be reverted. Levente > > Kind regards, > > Bart > > -- > imagination is more important than knowledge - Albert Einstein > Logic will get you from A to B. Imagination will take you everywhere - > Albert Einstein > Learn from yesterday, live for today, hope for tomorrow. The important thing > is not to stop questioning. - Albert Einstein > The true sign of intelligence is not knowledge but imagination. - Albert > Einstein > However beautiful the strategy, you should occasionally look at the results. > - Sir Winston Churchill > It's not enough that we do our best; sometimes we have to do what's > required. - Sir Winston Churchill > _______________________________________________ Pharo-project mailing list [hidden email] http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project |
Re: Why is Stack extending from LinkedList?
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In reply to this post by Lukas Renggli
On Thu, 26 Aug 2010, Lukas Renggli wrote:
> I wonder why there is the need for a stack class at all? > > OrderedCollection is the class designed to do Stacks and Queues > efficiently and portably, see #addFirst:, #addLast:, #first, #last, > #removeFirst, #removeLast. If so, then there are some problems: o := OrderedCollection new: 1000. 1 to: 1000 do: [ :each | o add: each ]. [ 100000 timesRepeat: [ o addFirst: o removeLast ] ] timeToRun. "===> 11660" Levente > > Lukas > > 2010/8/26 Bart Gauquie <[hidden email]>: >> Hi list, >> >> is there a specific reason Stack is extending from LinkedList, instead of >> using a LinkedList internally? >> To me, it seems that the protocol that LinkedList, SequenceableCollection, >> ... provides is not the protocol you expect from a Stack? >> >> Any thoughts on this? >> >> Kind regards, >> >> Bart >> >> -- >> imagination is more important than knowledge - Albert Einstein >> Logic will get you from A to B. Imagination will take you everywhere - >> Albert Einstein >> Learn from yesterday, live for today, hope for tomorrow. The important thing >> is not to stop questioning. - Albert Einstein >> The true sign of intelligence is not knowledge but imagination. - Albert >> Einstein >> However beautiful the strategy, you should occasionally look at the results. >> - Sir Winston Churchill >> It's not enough that we do our best; sometimes we have to do what's >> required. - Sir Winston Churchill >> >> _______________________________________________ >> Pharo-project mailing list >> [hidden email] >> http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project >> > > > > -- > Lukas Renggli > www.lukas-renggli.ch > > _______________________________________________ > Pharo-project mailing list > [hidden email] > http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project > _______________________________________________ Pharo-project mailing list [hidden email] http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project |
Re: Why is Stack extending from LinkedList?
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In my machine:
o := OrderedCollection new: 1000. 1 to: 1000 do: [ :each | o add: each ]. [ 100000 timesRepeat: [ o addFirst: o removeLast ] ] timeToRun. ==> 12842 o := LinkedList new: 1000. 1 to: 1000 do: [ :each | o add: each ]. [ 100000 timesRepeat: [ o addFirst: o removeLast ] ] timeToRun. ==> 5603 On Fri, Aug 27, 2010 at 1:35 PM, Levente Uzonyi <[hidden email]> wrote:
_______________________________________________ Pharo-project mailing list [hidden email] http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project |
Re: Why is Stack extending from LinkedList?
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In reply to this post by Levente Uzonyi-2
2010/8/27 Levente Uzonyi <[hidden email]>:
> On Thu, 26 Aug 2010, Lukas Renggli wrote: > >> I wonder why there is the need for a stack class at all? >> >> OrderedCollection is the class designed to do Stacks and Queues >> efficiently and portably, see #addFirst:, #addLast:, #first, #last, >> #removeFirst, #removeLast. > > If so, then there are some problems: > > o := OrderedCollection new: 1000. > 1 to: 1000 do: [ :each | o add: each ]. > [ 100000 timesRepeat: [ o addFirst: o removeLast ] ] timeToRun. "===> 11660" > > > Levente > OrderedCollection could be implemented differently, like for example having a circular array and maintaining a firstIndex and size instead of lastIndex. The main drawback would be that fast copy/replace would have to be split in two parts. Nicolas >> >> Lukas >> >> 2010/8/26 Bart Gauquie <[hidden email]>: >>> >>> Hi list, >>> >>> is there a specific reason Stack is extending from LinkedList, instead of >>> using a LinkedList internally? >>> To me, it seems that the protocol that LinkedList, >>> SequenceableCollection, >>> ... provides is not the protocol you expect from a Stack? >>> >>> Any thoughts on this? >>> >>> Kind regards, >>> >>> Bart >>> >>> -- >>> imagination is more important than knowledge - Albert Einstein >>> Logic will get you from A to B. Imagination will take you everywhere - >>> Albert Einstein >>> Learn from yesterday, live for today, hope for tomorrow. The important >>> thing >>> is not to stop questioning. - Albert Einstein >>> The true sign of intelligence is not knowledge but imagination. - Albert >>> Einstein >>> However beautiful the strategy, you should occasionally look at the >>> results. >>> - Sir Winston Churchill >>> It's not enough that we do our best; sometimes we have to do what's >>> required. - Sir Winston Churchill >>> >>> _______________________________________________ >>> Pharo-project mailing list >>> [hidden email] >>> http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project >>> >> >> >> >> -- >> Lukas Renggli >> www.lukas-renggli.ch >> >> _______________________________________________ >> Pharo-project mailing list >> [hidden email] >> http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project >> > > _______________________________________________ > Pharo-project mailing list > [hidden email] > http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project > _______________________________________________ Pharo-project mailing list [hidden email] http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project |
Re: Why is Stack extending from LinkedList?
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On Fri, 27 Aug 2010, Nicolas Cellier wrote:
> 2010/8/27 Levente Uzonyi <[hidden email]>: >> On Thu, 26 Aug 2010, Lukas Renggli wrote: >> >>> I wonder why there is the need for a stack class at all? >>> >>> OrderedCollection is the class designed to do Stacks and Queues >>> efficiently and portably, see #addFirst:, #addLast:, #first, #last, >>> #removeFirst, #removeLast. >> >> If so, then there are some problems: >> >> o := OrderedCollection new: 1000. >> 1 to: 1000 do: [ :each | o add: each ]. >> [ 100000 timesRepeat: [ o addFirst: o removeLast ] ] timeToRun. "===> 11660" >> >> >> Levente >> > > OrderedCollection could be implemented differently, like for example > having a circular array and maintaining a firstIndex and size instead > of lastIndex. This issue is already fixed in Squeak 4.1. I tried the OrderedCollection with a circular array just like you suggested, but it was a bit slower than Squeak's OrderedCollection. Also note that this is an edge case. Levente > > The main drawback would be that fast copy/replace would have to be > split in two parts. > > Nicolas > >>> >>> Lukas >>> >>> 2010/8/26 Bart Gauquie <[hidden email]>: >>>> >>>> Hi list, >>>> >>>> is there a specific reason Stack is extending from LinkedList, instead of >>>> using a LinkedList internally? >>>> To me, it seems that the protocol that LinkedList, >>>> SequenceableCollection, >>>> ... provides is not the protocol you expect from a Stack? >>>> >>>> Any thoughts on this? >>>> >>>> Kind regards, >>>> >>>> Bart >>>> >>>> -- >>>> imagination is more important than knowledge - Albert Einstein >>>> Logic will get you from A to B. Imagination will take you everywhere - >>>> Albert Einstein >>>> Learn from yesterday, live for today, hope for tomorrow. The important >>>> thing >>>> is not to stop questioning. - Albert Einstein >>>> The true sign of intelligence is not knowledge but imagination. - Albert >>>> Einstein >>>> However beautiful the strategy, you should occasionally look at the >>>> results. >>>> - Sir Winston Churchill >>>> It's not enough that we do our best; sometimes we have to do what's >>>> required. - Sir Winston Churchill >>>> >>>> _______________________________________________ >>>> Pharo-project mailing list >>>> [hidden email] >>>> http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project >>>> >>> >>> >>> >>> -- >>> Lukas Renggli >>> www.lukas-renggli.ch >>> >>> _______________________________________________ >>> Pharo-project mailing list >>> [hidden email] >>> http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project >>> >> >> _______________________________________________ >> Pharo-project mailing list >> [hidden email] >> http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project >> > > _______________________________________________ > Pharo-project mailing list > [hidden email] > http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project > _______________________________________________ Pharo-project mailing list [hidden email] http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project |
Re: Why is Stack extending from LinkedList?
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In reply to this post by Guillermo Polito
On Fri, 27 Aug 2010, Guillermo Polito wrote:
> In my machine: > > o := OrderedCollection new: 1000. > 1 to: 1000 do: [ :each | o add: each ]. > [ 100000 timesRepeat: [ o addFirst: o removeLast ] ] timeToRun. ==> 12842 > > o := LinkedList new: 1000. > 1 to: 1000 do: [ :each | o add: each ]. > [ 100000 timesRepeat: [ o addFirst: o removeLast ] ] timeToRun. ==> 5603 LinkedList should be used this way if you want to use it as a Queue: o := LinkedList new: 1000. 1 to: 1000 do: [ :each | o add: each ]. [ 100000 timesRepeat: [ o addLast: o removeFirst ] ] timeToRun. "===> 119" Levente > > > On Fri, Aug 27, 2010 at 1:35 PM, Levente Uzonyi <[hidden email]> wrote: > >> On Thu, 26 Aug 2010, Lukas Renggli wrote: >> >> I wonder why there is the need for a stack class at all? >>> >>> OrderedCollection is the class designed to do Stacks and Queues >>> efficiently and portably, see #addFirst:, #addLast:, #first, #last, >>> #removeFirst, #removeLast. >>> >> >> If so, then there are some problems: >> >> o := OrderedCollection new: 1000. >> 1 to: 1000 do: [ :each | o add: each ]. >> [ 100000 timesRepeat: [ o addFirst: o removeLast ] ] timeToRun. "===> >> 11660" >> >> >> Levente >> >> >> >>> Lukas >>> >>> 2010/8/26 Bart Gauquie <[hidden email]>: >>> >>>> Hi list, >>>> >>>> is there a specific reason Stack is extending from LinkedList, instead of >>>> using a LinkedList internally? >>>> To me, it seems that the protocol that LinkedList, >>>> SequenceableCollection, >>>> ... provides is not the protocol you expect from a Stack? >>>> >>>> Any thoughts on this? >>>> >>>> Kind regards, >>>> >>>> Bart >>>> >>>> -- >>>> imagination is more important than knowledge - Albert Einstein >>>> Logic will get you from A to B. Imagination will take you everywhere - >>>> Albert Einstein >>>> Learn from yesterday, live for today, hope for tomorrow. The important >>>> thing >>>> is not to stop questioning. - Albert Einstein >>>> The true sign of intelligence is not knowledge but imagination. - Albert >>>> Einstein >>>> However beautiful the strategy, you should occasionally look at the >>>> results. >>>> - Sir Winston Churchill >>>> It's not enough that we do our best; sometimes we have to do what's >>>> required. - Sir Winston Churchill >>>> >>>> _______________________________________________ >>>> Pharo-project mailing list >>>> [hidden email] >>>> http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project >>>> >>>> >>> >>> >>> -- >>> Lukas Renggli >>> www.lukas-renggli.ch >>> >>> _______________________________________________ >>> Pharo-project mailing list >>> [hidden email] >>> http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project >>> >>> >> _______________________________________________ >> Pharo-project mailing list >> [hidden email] >> http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project >> > _______________________________________________ Pharo-project mailing list [hidden email] http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project |
Re: Why is Stack extending from LinkedList?
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In reply to this post by Levente Uzonyi-2
On Aug 27, 2010, at 6:32 PM, Levente Uzonyi wrote: > On Thu, 26 Aug 2010, Bart Gauquie wrote: > >> Hi list, >> >> is there a specific reason Stack is extending from LinkedList, instead of >> using a LinkedList internally? >> To me, it seems that the protocol that LinkedList, SequenceableCollection, >> ... provides is not the protocol you expect from a Stack? >> >> Any thoughts on this? > > Originally it used encapsulation, when where? > but for some reason it was changed to use inheritance, probably for a "cleaner" system. IMHO the changes should be reverted. I was not aware that Stack was a subclass of linkedList, it looks again subclassing versus subtyping. And subtyping is better. Stef > > > Levente > >> >> Kind regards, >> >> Bart >> >> -- >> imagination is more important than knowledge - Albert Einstein >> Logic will get you from A to B. Imagination will take you everywhere - >> Albert Einstein >> Learn from yesterday, live for today, hope for tomorrow. The important thing >> is not to stop questioning. - Albert Einstein >> The true sign of intelligence is not knowledge but imagination. - Albert >> Einstein >> However beautiful the strategy, you should occasionally look at the results. >> - Sir Winston Churchill >> It's not enough that we do our best; sometimes we have to do what's >> required. - Sir Winston Churchill >> > > _______________________________________________ > Pharo-project mailing list > [hidden email] > http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project _______________________________________________ Pharo-project mailing list [hidden email] http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project |
Re: Why is Stack extending from LinkedList?
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On Fri, 27 Aug 2010, Stéphane Ducasse wrote:
> > On Aug 27, 2010, at 6:32 PM, Levente Uzonyi wrote: > >> On Thu, 26 Aug 2010, Bart Gauquie wrote: >> >>> Hi list, >>> >>> is there a specific reason Stack is extending from LinkedList, instead of >>> using a LinkedList internally? >>> To me, it seems that the protocol that LinkedList, SequenceableCollection, >>> ... provides is not the protocol you expect from a Stack? >>> >>> Any thoughts on this? >> >> Originally it used encapsulation, > > when where? Levente > >> but for some reason it was changed to use inheritance, probably for a "cleaner" system. IMHO the changes should be reverted. > > I was not aware that Stack was a subclass of linkedList, it looks again subclassing versus subtyping. And subtyping is better. > > Stef > >> >> >> Levente >> >>> >>> Kind regards, >>> >>> Bart >>> >>> -- >>> imagination is more important than knowledge - Albert Einstein >>> Logic will get you from A to B. Imagination will take you everywhere - >>> Albert Einstein >>> Learn from yesterday, live for today, hope for tomorrow. The important thing >>> is not to stop questioning. - Albert Einstein >>> The true sign of intelligence is not knowledge but imagination. - Albert >>> Einstein >>> However beautiful the strategy, you should occasionally look at the results. >>> - Sir Winston Churchill >>> It's not enough that we do our best; sometimes we have to do what's >>> required. - Sir Winston Churchill >>> >> >> _______________________________________________ >> Pharo-project mailing list >> [hidden email] >> http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project > > > _______________________________________________ > Pharo-project mailing list > [hidden email] > http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project > Pharo-project mailing list [hidden email] http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project |
Re: Why is Stack extending from LinkedList?
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> In Pharo 1.0 (and Squeak of course). I'm amazed. Our quality process seems weak :) I will check and revert it. Thanks for spotting that. Stef >>> but for some reason it was changed to use inheritance, probably for a "cleaner" system. IMHO the changes should be reverted. >> >> I was not aware that Stack was a subclass of linkedList, it looks again subclassing versus subtyping. And subtyping is better. >> >> Stef >> >>> >>> >>> Levente >>> >>>> >>>> Kind regards, >>>> >>>> Bart >>>> >>>> -- >>>> imagination is more important than knowledge - Albert Einstein >>>> Logic will get you from A to B. Imagination will take you everywhere - >>>> Albert Einstein >>>> Learn from yesterday, live for today, hope for tomorrow. The important thing >>>> is not to stop questioning. - Albert Einstein >>>> The true sign of intelligence is not knowledge but imagination. - Albert >>>> Einstein >>>> However beautiful the strategy, you should occasionally look at the results. >>>> - Sir Winston Churchill >>>> It's not enough that we do our best; sometimes we have to do what's >>>> required. - Sir Winston Churchill >>>> >>> >>> _______________________________________________ >>> Pharo-project mailing list >>> [hidden email] >>> http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project >> >> >> _______________________________________________ >> Pharo-project mailing list >> [hidden email] >> http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project > _______________________________________________ > Pharo-project mailing list > [hidden email] > http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project _______________________________________________ Pharo-project mailing list [hidden email] http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project |
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