clojure.core/with-local-vars

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Type: macro Added: Clojure 1.0 Examples: 3 Runnable: 0

([name-vals-vec & body])

varbinding=> symbol init-expr

Executes the exprs in a context in which the symbols are bound to vars with per-thread bindings to the init-exprs. The symbols refer to the var objects themselves, and must be accessed with var-get and var-set

Examples

by jafingerhut on 2012-03-08 . May have evaluation errors. ▶

;; with-local-vars allows you to write more imperative-style code, for cases ;; where you really want to. factorial isn't a case where it helps, but ;; it is short and familiar. Note that (var-get acc) can be abbreviated ;; as @acc (defn factorial [x] (with-local-vars [acc 1, cnt x] (while (> @cnt 0) (var-set acc (* @acc @cnt)) (var-set cnt (dec @cnt))) @acc)) #'user/factorial (factorial 7) 5040

by didibus on 2017-04-18 . May have evaluation errors. ▶

(with-local-vars [a-local-var-variable "value"] ;; If you use the symbol by itself, you get the Var back (println a-local-var-variable) ;; So when using local var variables, you must explicitly ;; get the value inside the Var (println (var-get a-local-var-variable)) ;; You can also get the value of a Var by using deref (println (deref a-local-var-variable)) ;; Or the @ reader macro (println @a-local-var-variable))

by char16t on 2017-07-16 . May have evaluation errors. ▶

;; with-local-vars allows you to write more imperative-style code, for cases ;; where you really want to. This example demonstrate how to change variable value ;; like in for-loop. There used doseq instead of for, because `for` is a macro ;; that generates lazy sequence that will be realized out of ranges ;; with-local-vars block (with-local-vars [n 0] (doseq [x (range 3)] (do (var-set n (inc (var-get n))) (println (var-get n))))) ; 1 ; 2 ; 3 ;=> nil

See also

• clojure.core/with-bindings
• clojure.core/var-set (1)
• clojure.core/volatile!
• clojure.core/var-get (1)

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