>>> Is there a good reason not to make Point a subclass of Number?
>>
>> Yes, points are not magnitudes! The definition of #< in Point contains the
>> note:
>>    "Answer whether the receiver is above and to the left of aPoint."
>> while #> contains the comment:
>>    "Answer whether the receiver is below and to the right of aPoint."
>...
> I have had reason to sort Points quite often, and have always done so
> using the following sort block:
>
> [:a :b | a y = b y ifTrue: [a x < b x] ifFalse: [a y < b y]]
>
> True, it establishes a convention, but I've never wanted ambiguous sorting of
> Points. Why not change the definition of < for Point.

(1) What are some of the reasons you (Travis) or anyone has had to
    sort Points linearly?

(2) Why not implement the range comparison messages to
    #shouldNotImplement or something like that?

(3) Point is a two-dimensional value. It cannot be made linear. Maybe
    the Block above works for a specific purpose. But it is no better
    than the relational comparison definitions, above. I'd vote for
    (#2), throwing an exception, as the simplest solution that makes
    the most general sense. YMMV.

>What are the arguments against turning the heirarchy there upside down? IOW
>
>Object
>    ArithmeticValue
>        LinearMagnitude
>            Number
>        Point

Some Magnitudes should not implement the math messages.

-- 
Patrick Logan                 mailto:patrickl at gemstone.com
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