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 <[email protected]> wrote:
From: Miguel Enrique Cobá Martínez <[email protected]>
Subject: [Newbies] Array vs OrderedCollection
To: "A friendly place to get answers to even the most basic questions about Squeak."
<[email protected]>
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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