compare-and-set!

function

since v0.0-927

clojure.core/compare-and-set!

Edit

Details:

Examples:

(def a (atom "abc"))

(compare-and-set! a "abc" "def")
;;=> true

@a
;;=> "def"

(compare-and-set! a "abc" "def")
;;=> false

@a
;;=> "def"

See Also:

• atom
• reset!
• swap!

Atomically sets the value of atom to newval if and only if the
current value of the atom is equal to oldval. Returns true if
set happened, else false.

(defn compare-and-set!
  [^not-native a oldval newval]
  (if (= (-deref a) oldval)
    (do (reset! a newval) true)
    false))