[armedbear-devel] eql for java objects

Kevin Reid kpreid at switchb.org
Sun Apr 25 12:50:06 UTC 2010

On Apr 25, 2010, at 6:55, Tobias C. Rittweiler wrote:

> I think that's past Alan's point which, from my understanding, is  
> simply
> "Java enums should be comparable by EQL." Makes perfect sense as EQL  
> is
> for object identity.

FWIW, I think it makes sense to have EQL compare “deeply” anything  
which is a strictly (outside of using explicitly write-to-arbitrary- 
memory operations) immutable “box”. Such immutability is rare in CL:  
characters and numbers happen to be its only occurrences. But the  
spirit of the thing, it seems to me, is to make EQL hide distinctions  
which are of no use whatsoever to the end programmer.

(Note that by strictly immutable I mean that you can't change *what  
object the box contains*, not that you can't mutate the object the box  
contains if that object is mutable.)

> Rather provide an EXT:EQUIVALENT generic function (or some small
> protocol) which can a) be extended by the user, b) hooks into however
> Java does it (Comparable?).

Object.equals(Object), actually.

Kevin Reid                                  <http://switchb.org/kpreid/>

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