Clojurians Log v2

Hi Brave and True folks

I’m still not super clear on destructuring. I’m on the macros chapter doing ex. 3. I have the 1-arity version working. But the single vector version doesn’t work, and I’m confused about how the destructuring syntax should work.

(defmacro create-attrs-fn
  ([fnname attribute]
   `(def ~fnname (comp ~attribute :attributes)))
  ([[fnname attribute & remaining]]
   (do (create-attrs-fn fnname attribute
        (create-attrs-fn remaining)))))

because of not understanding destructuring I can’t figure out what’s the arity of my functions.

For example:

(defn mytest [fnname attribute] "nothing")
(:arglists (meta #'mytest))
;=> ([fnname attribute]) 

(defn mytest [[fnname attribute & remaining] v] "nothing")
(:arglists (meta #'mytest))
;=> ([[fnname attribute & remaining] v])

I’m using this from SO:

(defn arg-count [f]
  (let [m (first (.getDeclaredMethods (class f)))
        p (.getParameterTypes m)]
    (alength p)))

Hmm… I don’t get what’s up from my error messages.

(defn mytest [[fnname attribute & remaining]] "nothing")
(arg-count mytest)
; => 1

(defmacro create-attrs-fn
  ([[fnname attribute & remaining]]
   (do (create-attrs-fn fnname attribute)
       (create-attrs-fn ~remaining)))
  ([fnname attribute]
   `(def ~fnname (comp ~attribute :attributes))))

:man-shrugging: