Array vs OrderedCollection

> Hi all,
>
> are there any reason to prefer:
>
> "adding 2 objects"
> array := Array with: anObject.
> array := array copyWith: aSecondObject
> "removing object"
> array := array copyWithout: aSecondObject.
>
> instead of:
>
> "adding 2 objects"
> oc := OrderedCollection new.
> oc add: anObject.
> oc add: aSecondObject.
> "removing object"
> oc remove: aSecondObject ifAbsent: []
>
> This in reference to
>
> Class >> addSubclass: and Class >> removeSubclass: methods

> From: Miguel Enrique Cobá Martínez <[hidden email]>
> Subject: [Newbies] Array vs OrderedCollection
> To: "A friendly place to get answers to even the most basic questions about Squeak." <[hidden email]>
> Date: Sunday, April 26, 2009, 5:00 PM
> Hi all,
>
> are there any reason to prefer:
>
> "adding 2 objects"
> array := Array with: anObject.
> array := array copyWith: aSecondObject
> "removing object"
> array := array copyWithout: aSecondObject.
>
> instead of:
>
> "adding 2 objects"
> oc := OrderedCollection new.
> oc add: anObject.
> oc add: aSecondObject.
> "removing object"
> oc remove: aSecondObject ifAbsent: []
>
> This in reference to
>
> Class >> addSubclass: and Class >>
> removeSubclass: methods
>
> Thanks for any answers
> Miguel Cobá
> _______________________________________________
> Beginners mailing list
> [hidden email]
> http://lists.squeakfoundation.org/mailman/listinfo/beginners

> On 4/27/09, Miguel Enrique Cobá Martínez <[hidden email]> wrote:
>> Hi all,
>>
>> are there any reason to prefer:
>>
>> "adding 2 objects"
>> array := Array with: anObject.
>> array := array copyWith: aSecondObject
>> "removing object"
>> array := array copyWithout: aSecondObject.
>>
>> instead of:
>>
>> "adding 2 objects"
>> oc := OrderedCollection new.
>> oc add: anObject.
>> oc add: aSecondObject.
>> "removing object"
>> oc remove: aSecondObject ifAbsent: []
>>
>> This in reference to
>>
>> Class >> addSubclass: and Class >> removeSubclass: methods
>
>
> In this particular case, I think you've made a valid point. I can't
> see any obvious reason why an OrderedCollection can't be used. My
> first suspicion is that this code was written before
> OrderedCollections were added to the system (i.e. in 1980 sometime).
> It might also have been written this way to make sure that the image
> could potentially run without an OrderedCollection class (e.g. when
> bootstrapping an image or something).
>

>
> Hi Miguel,
>
> The answer depends on what you are doing.
>
> Arrays are compact fixed size entities. OrderedCollections are less compact and less fixed size.
>
> If you are building a list by adding objects to it. Don't care to know the maximum size in advance. Or need a stack like object, OrderedCollections are your class of object.
>
> Once you are done building. Know the exact size and know that few changes to the list will be needed. Array is good.
>
> Many things should not care whether the collection is one or the other as far as messages go. Performance will usually favor Arrays when the size is not changing.
>
> So do you want random access to your collection?
> Or do you need to easily add or remove things from the ends?
>
> It is easy to have it both ways. When the processing favors OrderedCollections use asOrderedCollection to insure the class.
> When random access rather than growth is needed use asArray.
>
> Don't care? Leave it be. Most language will work with either.
>
> Also some objects already have preferences. Streams currently expect their contents to be Arrays.
> Strings expect to be arrays of Characters.
>
> I have found no I-can-plan-in-advance type rules for this. I find myself annoyed when the code requires I actually choose.
>
> I usually aim for using Arrays. And if the code fights me on this I use OrderedCollections.
>
> If I want a stack then I need ordered collection using addLast: item and removeLast for push and pop. I found this out after reading Kent Beck's book on Smalltalk best practice pattens.
>
> Yours in curiosity and service, --Jerome Peace

>
> --- On Sun, 4/26/09, Miguel Enrique Cobá Martínez <[hidden email]> wrote:
>
>> From: Miguel Enrique Cobá Martínez <[hidden email]>
>> Subject: [Newbies] Array vs OrderedCollection
>> To: "A friendly place to get answers to even the most basic questions about Squeak." <[hidden email]>
>> Date: Sunday, April 26, 2009, 5:00 PM
>> Hi all,
>>
>> are there any reason to prefer:
>>
>> "adding 2 objects"
>> array := Array with: anObject.
>> array := array copyWith: aSecondObject
>> "removing object"
>> array := array copyWithout: aSecondObject.
>>
>> instead of:
>>
>> "adding 2 objects"
>> oc := OrderedCollection new.
>> oc add: anObject.
>> oc add: aSecondObject.
>> "removing object"
>> oc remove: aSecondObject ifAbsent: []
>>
>> This in reference to
>>
>> Class >> addSubclass: and Class >>
>> removeSubclass: methods
>>
>> Thanks for any answers
>> Miguel Cobá
>> _______________________________________________
>> Beginners mailing list
>> [hidden email]
>> http://lists.squeakfoundation.org/mailman/listinfo/beginners
>
>
>      
> _______________________________________________
> Beginners mailing list
> [hidden email]
> http://lists.squeakfoundation.org/mailman/listinfo/beginners
>

> Jerome Peace wrote:
> >
> >Hi Miguel,
> >
> >The answer depends on what you are doing.
> >
> >Arrays are compact fixed size entities. OrderedCollections are less
> >compact and less fixed size.
> >
> >If you are building a list by adding objects to it. Don't care to know the
> >maximum size in advance. Or need a stack like object, OrderedCollections
> >are your class of object.
> >
> >Once you are done building. Know the exact size and know that few changes
> >to the list will be needed. Array is good.
> >
> >Many things should not care whether the collection is one or the other as
> >far as messages go. Performance will usually favor Arrays when the size is
> >not changing.
> >
> >So do you want random access to your collection?
> >Or do you need to easily add or remove things from the ends?
> >
> >It is easy to have it both ways. When the processing favors
> >OrderedCollections use asOrderedCollection to insure the class.
> >When random access rather than growth is needed use asArray.
> >
> >Don't care? Leave it be. Most language will work with either.
> >
> >Also some objects already have preferences. Streams currently expect their
> >contents to be Arrays.
> >Strings expect to be arrays of Characters.
> >
> >I have found no I-can-plan-in-advance type rules for this. I find myself
> >annoyed when the code requires I actually choose.
> >
> >I usually aim for using Arrays. And if the code fights me on this I use
> >OrderedCollections.
> >
> >If I want a stack then I need ordered collection using addLast: item and
> >removeLast for push and pop. I found this out after reading Kent Beck's
> >book on Smalltalk best practice pattens.
> >
> >Yours in curiosity and service, --Jerome Peace
>
> Thanks for your advise. I think that as the array is a VM-aware type, it
> is implemented as native code. Maybe that is not the case with the
> ordered colection, that is byte code compiled.

> On Sun, Apr 26, 2009 at 10:08:54PM -0500, Miguel Enrique Cob? Mart?nez wrote:
>> Jerome Peace wrote:
>>> Hi Miguel,
>>>
>>> The answer depends on what you are doing.
>>>
>>> Arrays are compact fixed size entities. OrderedCollections are less
>>> compact and less fixed size.
>>>
>>> If you are building a list by adding objects to it. Don't care to know the
>>> maximum size in advance. Or need a stack like object, OrderedCollections
>>> are your class of object.
>>>
>>> Once you are done building. Know the exact size and know that few changes
>>> to the list will be needed. Array is good.
>>>
>>> Many things should not care whether the collection is one or the other as
>>> far as messages go. Performance will usually favor Arrays when the size is
>>> not changing.
>>>
>>> So do you want random access to your collection?
>>> Or do you need to easily add or remove things from the ends?
>>>
>>> It is easy to have it both ways. When the processing favors
>>> OrderedCollections use asOrderedCollection to insure the class.
>>> When random access rather than growth is needed use asArray.
>>>
>>> Don't care? Leave it be. Most language will work with either.
>>>
>>> Also some objects already have preferences. Streams currently expect their
>>> contents to be Arrays.
>>> Strings expect to be arrays of Characters.
>>>
>>> I have found no I-can-plan-in-advance type rules for this. I find myself
>>> annoyed when the code requires I actually choose.
>>>
>>> I usually aim for using Arrays. And if the code fights me on this I use
>>> OrderedCollections.
>>>
>>> If I want a stack then I need ordered collection using addLast: item and
>>> removeLast for push and pop. I found this out after reading Kent Beck's
>>> book on Smalltalk best practice pattens.
>>>
>>> Yours in curiosity and service, --Jerome Peace
>> Thanks for your advise. I think that as the array is a VM-aware type, it
>> is implemented as native code. Maybe that is not the case with the
>> ordered colection, that is byte code compiled.
>
> Array is an ordinary class, just like OrderedCollection. The VM is aware
> of class Array only in the sense that it has hooks to create instances of
> Array from within the VM, but the actual instances are objects just like
> other object.
>

>> But besides that, a OrderedCollection is more versatile than an Array.
>> Anyway, I think that for my code, as is more focused to adding and
>> removing objects and for this, an OrderedCollection is the best choice.
>
> Yes, good choice.
>
> Dave
>  
> _______________________________________________
> Beginners mailing list
> [hidden email]
> http://lists.squeakfoundation.org/mailman/listinfo/beginners
>