On Thu, Aug 4, 2011 at 9:22 AM, Stéphane Ducasse <stephane.ducasse@inria.fr>wrote:
On Aug 4, 2011, at 9:10 AM, Jonathan Kelly wrote:
Hi,
firstly, is there somewhere that explains what the icons in the system browser signify? (eg the three coloured dots)?
... are for collections
More importantly (to me anyway) ... I'm confused - why at: is defined in Object and not SequenceableCollection?
at: in Object is because some Object like array have variable size #(1 2 3) #() Array new: 6
have all different sizes
How this is encoded? when you create a class you use variableSubclass: instead of subclass:
Now how to access such elements? using at: and this is not only for Array.
BTW Collection subclass: #SequenceableCollection so Sequenceable is not a variable class just an abstract class.
Now Object>>at: index "Primitive. Assumes receiver is indexable. Answer the value of an indexable element in the receiver. Fail if the argument index is not an Integer or is out of bounds. Essential. See Object documentation whatIsAPrimitive. Read the class comment for a discussion about that the fact that the index can be a float."
That's a great explanation. You can read more about that in a post I did a couple of months ago: http://marianopeck.wordpress.com/2011/05/07/class-formats-and-compiledmethod... Those I call "variable" are those where you can use #at: #at:put: for example, etc... -- Mariano http://marianopeck.wordpress.com