Dynamic vars + copy-ns

[galdolber]

version

{:sha "75117e6139d0026d4dd035932862134a21c2c41a"}

platform

Mac V.11.2.3

problem

When using sci/copy-ns of a namespace that contains dynamic vars, the dynamic vars are not working in the interpreter.

repro

(ns clojure-ns) (def ^:dynamic *var*)

*** Start a sci runtime with***
(sci/init {:namespaces {'clojure-ns (sci/copy-ns clojure-ns (sci/create-ns 'clojure-ns nil))} :features #{:clj :cljs}})

*** Inside the sci runtime***
(binding [clojure-ns/*var* true] clojure-ns/*var* )

Getting error: Can't dynamically bind non-dynamic var ***

expected behavior

No error

I checked the code under vars.cljc, I think its not possible to do this as the dynamic vars inside the interpreter are managed completely differently, but please let me know if there's a way to do it. What I'm looking for is a way to interop from sci to the clojure(script) code transparently with common dynamic vars.

Sponsor

[borkdude]

@galdolber I pushed b5b550a now which includes dynamic metadata.

You're right, SCI has its own way of dealing with dynamic vars. It is decoupled from Clojure since any Clojure dialect has a different way of dealing with vars and also because SCI's context is fully isolated from the host: you don't want to have any Clojure vars in there which could cause safety issues.

To deal with this case, what I've done in several projects, including babashka, is wrap functions that need to see the binding from the host:

(ns sci.examples.dynamic-vars
  (:require [sci.core :as sci]))

(def ^:dynamic *items* 10)

(defn foo [] (+ *items* 12))

(def mns (sci/create-ns 'my.namespace nil))

(def items (sci/copy-var *items* mns))

(defn sci-foo []
  (binding [*items* @items]
    (foo)))

(def ctx
  (sci/init {:namespaces
             {'my.namespace {'foo (sci/copy-var sci-foo mns {:name 'foo})
                             '*items* items}}}))

(prn (sci/eval-string* ctx "
(require '[my.namespace :as m])
(binding [m/*items* 1337] (m/foo))"))
;; => 1349

[galdolber]

Thanks! that worked!