SO as a complete hack to get file and line number metadata I
implemented this macro, my file of rules is now just loaded with load-
file and the rules that are define in it with RULE have the
appropriate file and line associated with them. This is compete abuse
of DEF and maybe the compiler (although it's not too dissimilar from
very valid approaches in common lisp), but is this creating any
ridiculous side effects that I should be aware of? is using the same
symbol to def to over and over and over again bad? register rule is
what takes care of putting the rule that was constructed where I need
it to be.
in common lisp I would use a progn here I used a let with no bindings,
is there a better way in clojure?
(defmacro RULE
"macro for creating an registering a rule"
[& params]
;; is there a way to do this without the let? this is progn?
`(let []
;;def is used as a hack to get file name and line number metadata
;; arguably instead of using a repeated symbol, rules could be
;; def'ed to their own name, except that would create a lot of
vars
;; which likely are never needed and would waste memory?
(def r# (verify-name (struct-map rule ~...@params)))
;; gets the metatdata from the var, but changes :name to rule's
name
(let [reg-r# (with-meta r# (assoc (meta (var r#)) :name (:name
r#)))]
(register-rule reg-r#)
reg-r#)))
On Apr 17, 10:48 am, Per Vognsen <per.vogn...@gmail.com> wrote:
> On Sat, Apr 17, 2010 at 2:29 AM, Kevin Livingston
>
> <kevinlivingston.pub...@gmail.com> wrote:
> > I have an application that will read in a large number of structures
> > from a file. those structures will be used throughout the application
> > to produce additional data etc. since they are "user" configurable,
> > it would be nice to know where they come from should one of them start
> > misbehaving. the type of metadata the compiler associates with
> > function definitions etc. would be very valuable. if I'm reading my
> > structures in with (read) is there anyway to get it to attach filename
> > and line-number etc. metadata?
>
> The reader doesn't do that but you can easily do it yourself if you
> only want to annotate top-level values.
>
> Thinking about this made me realize that it would be nice if the
> reader reentered itself (as it does in LispReader's
> readDelimitedList() and a few other contexts) through a var so it
> could be rebound by a programmer. Then you could inject your own line
> number annotation into the reader which would apply not only to
> top-level values (e.g. a vector literal) but also its subvalues (e.g.
> the elements of the vector literal).
>
> -Per
>
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