Object orientation  can you have too much of a good thing?
HansMartin Mosner
hmm at heeg.de
Mon Oct 29 06:53:28 UTC 2007
Blake schrieb:
> On Sun, 28 Oct 2007 01:32:34 0800, Michael Davies
> <mykdavies+squeak at gmail.com> wrote:
>
>> There's an interesting post and discussion here:
>> http://weblog.raganwald.com/2007/10/toomuchofgoodthingnotall.html
>
> I know we wrestle with symmetry from timetotime but is it true that:
>
> 1 + 2.0
>
> should yield the same result as
>
> 2.0 + 1
>
> ?
>
>
For the current arithmetic implementation in Smalltalk, yes (in either
case the integer is converted to a float, and those two floats are
added. Floating point addition is commutative).
In general, a + b can be unequal to b + a, for example, if you implement
the #+ method in class String to mean concatenation.
Even in mathematical notations, there are operator symbols which are
commutative when used with scalars and noncommutative when used with
other mathematical objects.
Cheers,
HansMartin
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