> Double dispatching in Smalltalk model, as I understand it,
> goes like this (using Haskell keywords for integers):
>
> Int, being a more primitive type, does not have to know how to
> cope with Integer in the situations like this: Int * Integer.
> So the method (*) in Int class has a hook for mixed arithmetic
> with any, not necesserily Integer, object - it just dispatches
> this expression again, after it sees that the other object is not
> Int - but this time as "Integer * Int".
!!! Surely after the recent discussion re numerical algorithms and a
new class structure for the algebraic hierarchy we all know that this
is no good. The binary operations (*), (+) etc are not commutative on
all types, notably Float. But the idea is sound, as long as you have
both a left and a right multiplication as class methods.
--KW 8-)
--
: Keith Wansbrough, MSc, BSc(Hons) (Auckland) -------------------------:
: PhD Student, Computing Science, University of Glasgow, Scotland. :
: Native of Antipodean Auckland, New Zealand: 174d47' E, 36d55' S. :
: http://www.dcs.gla.ac.uk/~keithw/ mailto:[EMAIL PROTECTED] :
:----------------------------------------------------------------------:
