I'm trying to extend-protocol for numbers and various other types (incl.
collections & nil) in CLJS, so have been doing something like this (reduced
email version):

(defprotocol PDeltaEq (delta= [a b]))

(extend-protocol PDeltaEq
  js/Number
  (delta= [a b] :yay)

  nil
  (delta= [_ b] (nil? b)))

(delta= 1 1)
;; :yay

(delta= 0 0)
Error: No protocol method Foo.foo defined for type number: 0

Now I guessed, this might have something to do with JS' considering 0 as
`false` somewhere in the internal protocol machinery... and I was right!
Here's a relevant excerpt from the compiled protocol dispatch fn:

var delta_EQ___2 = function(a, b) {
  if (function() {
    var and__3466__auto__ = a;
    if (and__3466__auto__) {
      return a.thi$ng$common$math$core$PDeltaEq$delta_EQ_$arity$2;
    } else {
      return and__3466__auto__;
    }
  }()) {
    return a.thi$ng$common$math$core$PDeltaEq$delta_EQ_$arity$2(a, b);
  } else {
    ....
  }
};

Obviously, with the `a` arg being 0, that `if (and__3466__auto__)` check is
always failing, so shouldn't this check be rewritten as:

if (goog.isDefAndNotNull(and__3466__auto__) &&
    a.thi$ng$common$math$core$PDeltaEquals$delta_EQ_$arity$2) {
  return a.thi$ng$common$math$core$PDeltaEquals$delta_EQ_$arity$2;
}
...

This change seems to fix this kind of error and AFAIK doesn't impact any of
my other (30+) test cases for this protocol...

Thoughts? :)

Thanks, K.

-- 
You received this message because you are subscribed to the Google
Groups "Clojure" group.
To post to this group, send email to clojure@googlegroups.com
Note that posts from new members are moderated - please be patient with your 
first post.
To unsubscribe from this group, send email to
clojure+unsubscr...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/clojure?hl=en
--- 
You received this message because you are subscribed to the Google Groups 
"Clojure" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to clojure+unsubscr...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

Reply via email to