On Tue, Apr 30, 2013 at 11:00 AM, Tassilo Horn <[email protected]> wrote:
> Gary Trakhman <[email protected]> writes:
>
> > If you're passing the var itself, I don't see why you'd need a macro.
> > If you want to check the namespace for a var matching an unquoted
> > symbol, you could do that in a macro.
>
> In case you really don't have the var itself but just its value, then
> "unbound" is a value, too, and you could check for it using
>
> (instance? clojure.lang.Var$Unbound *x*)
> ;=> true
>
> nice one, thanks!
I was thinking just in case any of these "clojure.lang.Var$Unbound" change
in the future, maybe I'd do something like this:
=>* (def uniqsym (gensym))*
#'jme3test1.x1/uniqsym
=> *uniqsym*
G__1603
=>* (defmacro defus [] `(def ~uniqsym))*
#'jme3test1.x1/defus
=> *(defus)*
#'jme3test1.x1/G__1603
=> *(class (eval uniqsym))*
clojure.lang.Var$Unbound
=> *(def unbound-class (class (eval uniqsym)))*
#'jme3test1.x1/unbound-class
=>* unbound-class*
clojure.lang.Var$Unbound
=> *(def ^:dynamic *x*)*
#'jme3test1.x1/*x*
=>* (instance? unbound-class *x*)*
true
=>* (binding [*x* 1]
(instance? unbound-class *x*)
)*
false
=>* (def ^:dynamic *x* 2)*
#'jme3test1.x1/*x*
=>* (binding [*x* 1]
(instance? unbound-class *x*)
)*
false
instead of
>
> (not (bound? #'*x*))
>
> Bye,
> Tassilo
>
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