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Lars Thomas Hansen <lth@xxxxxxxxxxx> writes:
> I hacked up a sample implementation that, as far as I can tell, covers
> the entire specification (Alternative 1 because I'm lazy).
Thanks! That looks pretty good. Two nits:
> (define-syntax set! let*
> (syntax-rules ()
> ((set! (?e0 ?e1 ...) ?v)
> ((setter ?e0) ?e1 ... ?v))
> ((set! ?i ?v)
> (set! ?i ?v))))
Why the question-marks? It makes it look like they have
some syntactic signifigance, but it is really just a
naming convention. Is it a common naming convention?
I haven't really it noticed before. To me (who have done
my of my programing in C/C++/Java), the question marks are
visually distracting.
> (set-setter!
> (lambda (proc setter)
> (set! setters (cons (cons proc setter) setters))
> (unspecified))))
Some implementors may just use the sample implementation,
though that is of course a bad idea for code that actually
uses setters heavily. We could at least make sure that the
setters list doesn't fill up with duplicates. (I realize I did
propose that changing a setter should be undefined, in which
case the concern duplicates is irrelevant. However, you yourself
suggested that we should allow setters to be redefined.)
(set-setter!
(lambda (proc setter)
(let ((probe (assq proc setters)))
(if probe
(set-cdr! probe setter)
(set! setters (cons (cons proc setter) setters))))
(unspecified))))
--
--Per Bothner
per@xxxxxxxxxxx http://www.bothner.com/~per/