CODEWITHSUNDEEP
clojure
Ryan Watts
Ryan Watts

Reputation: 11

Calling Clojure Functions Loaded from File

I am working on a clojure DSL for guitar tablature and I want to allow users to write plugins by defining a function called apply-clojure-plugin in a known file location (say plugins.clj).

I've tried:

I'm guessing it is some sort of namespace issue but I can't quite make out how to use ns-resolve here (if it's even necessary).

EDIT: I ended up solving this with resolve. The issue was that apply-clojure-plugin isn't defined at compile time (since it is defined in the file), so an error is thrown during compilation. Calling (resolve 'apply-clojure-plugin) works fine.

Upvotes: 1

Views: 228

Answers (1)

noisesmith
noisesmith

Reputation: 20194

You either want (load "plugins") (if the directory containing the file is on the classpath), or (load-file "path/to/plugins.clj") to load from a known file path relative to the execution (or absolute path).

If the file contains no ns form, you will be able to access its definitions directly. Otherwise, you will need to know which ns the file defines, and you can use alias to map that namespace into your own:

;; make a new namespace for demonstration purposes
:user=> (ns foo)
nil
;; a definition in the other namespace
:foo=> (def bar "hello")
#'foo/bar
;; switch back to the original namespace
:foo=> (in-ns 'user)
#object[clojure.lang.Namespace 0x14a50707 "user"]
;; our definition is not visible
:user=> (resolve 'bar)
nil
;; but it is visible based on the fully qualified namespace
+user=> (resolve 'foo/bar)
#'foo/bar
;; using alias, we can make a convenient shorthand
+user=> (alias 'f 'foo)
nil
+user=> f/bar
"hello"

Upvotes: 2

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