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."
>
> Jonathan.
>
