clojure - eval code in different namespace

Question

I\'m coding something like REPL Server. Request from users evaluates in such function:

(defn execute [request]
  (str (try
          (eval (read-string request))         


        

Answer 1

Solved:

(binding [*ns* user-ns] (eval (read-string request)))

Answer 2

You can write a macro that mimics

(defmacro my-eval [s] `~(read-string s))

It works better that eval because the symbol resolution of s occurs in the context that calls my-eval. Thanks to @Matthias Benkard for the clarifications.

Answer 3

(symbol (str "client-" (Math/abs (.nextInt random)))

I just wanted to add, that this could be achieved with

(gensym "client-")

(I wanted to comment, but it turns our that I can't :))

Answer 4

Changing namespace means that you will have to reinitialize all the aliases, or refer to even clojure.core stuff with a fully qualified name:

user=> (defn alien-eval [ns str]
         (let [cur *ns*]
           (try ; needed to prevent failures in the eval code from skipping ns rollback
             (in-ns ns)   
             (eval (read-string str))
             (finally 
               (in-ns (ns-name cur))
               (remove-ns ns))))) ; cleanup, skip if you reuse the alien ns
#'user/alien-eval
user=> (alien-eval 'alien "(clojure.core/println clojure.core/*ns*)") ; note the FQN
#<Namespace alien> ; the effect of println
nil                ; the return value of alien-eval