Forward-declaring a var from another namespace in Clojure?

clojure

Solution

I think the solution you already have is the easiest one. If you wrap it into a macro it doesn't even look that bad anymore:

(defmacro declare-extern
  [& syms]
  (let [n (ns-name *ns*)]
     `(do 
        ~@(for [s syms]
            `(do 
               (ns ~(symbol (namespace s)))
               (declare ~(symbol (name s)))))
        (in-ns '~n))))

Call it with:

(declare-extern my.extern.ns/abc) ;; => #<Namespace ...>
my.extern.ns/abc                  ;; => #<Unbound Unbound: #'my.extern.ns/abc>

Problem

I know how to forward declare a var for the current namespace. Instead, I want to declare a var from another namespace. How do I do this? This will help me eliminate a circular load dependency. At the moment, this is what I've tried: ``` ; this_ns.clj (ns my-project.this-ns (:require ...)) (ns my-project.other-ns) (declare other-func) (ns my-project.this-ns) ; return to original namespace (defn func-1 [] (my-project.other-ns/other-func)) ``` It works, but I don't like it.

Original source