[squeak-dev] Re: Circular definitions of size and do:
rpolkinghorne at groupwise.swin.edu.au
Mon Oct 3 03:51:12 UTC 2011
>> Is this considered a bug, or a learning experience for new players?
By "this", I meant the consequence of my error (expected "Error: Foo
needs a method for size", got a hung image), and the effort required
to find its cause. I agree with Eliot's suggestion, that
SequenceableCollection>>size should raise an error.
> You should not instantiate an abstract class.
To follow that advice, I'd need a way to find out which classes were
abstract, and when I'd implemented enough methods to stop them being
abstract. That seems to be a black art in Smalltalk.
There are two ways I could have written this. One is to define a
subclass of Collection, and use the built-in collect:, inject:into:
and so on. The other is to subclass Object, and define the iterators
that I was going to use. Which approach is more common?
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