[Newbies] Array vs OrderedCollection

[Miguel Enrique Cobá Martínez]

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.

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.

Thank you again,
Miguel Cobá
> 
> --- On Sun, 4/26/09, Miguel Enrique Cobá Martínez <miguel.coba at gmail.com> wrote:
> 
>> From: Miguel Enrique Cobá Martínez <miguel.coba at gmail.com>
>> Subject: [Newbies] Array vs OrderedCollection
>> To: "A friendly place to get answers to even the most basic questions about Squeak." <beginners at lists.squeakfoundation.org>
>> 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
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> 
> 
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