Created
October 1, 2013 18:56
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prevent infinite print recursion for IDeref
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;; As originally posted, circa July 2009: http://web.archive.org/web/20110919081924/http://paste.lisp.org/display/83647 | |
(def *iderefs* #{}) | |
(defmethod print-method clojure.lang.IDeref [o #^Writer w] | |
(if (*iderefs* o) | |
(.write w (format "#<%s@%x>" | |
(.getSimpleName (class o)) | |
(System/identityHashCode o))) | |
(binding [*iderefs* (conj *iderefs* o)] | |
(print-sequential (format "#<%s@%x: " | |
(.getSimpleName (class o)) | |
(System/identityHashCode o)) | |
pr-on, "", ">" | |
(list (if (and (future? o) (not (future-done? o))) | |
:pending | |
@o)) | |
w)))) | |
;; === without 'future' support === | |
(def *iderefs* #{}) | |
(defmethod print-method clojure.lang.IDeref [o #^Writer w] | |
(if (*iderefs* o) | |
(.write w (format "#<%s@%x>" | |
(.getSimpleName (class o)) | |
(System/identityHashCode o))) | |
(binding [*iderefs* (conj *iderefs* o)] | |
(print-sequential (format "#<%s@%x: " | |
(.getSimpleName (class o)) | |
(System/identityHashCode o)) | |
pr-on, "", ">", (list @o), w)))) | |
;; === manual binding scope, without future === | |
(def *iderefs* #{}) | |
(defmethod print-method clojure.lang.IDeref [o #^Writer w] | |
(if (*iderefs* o) | |
(.write w (format "#<%s@%x>" | |
(.getSimpleName (class o)) | |
(System/identityHashCode o))) | |
(do | |
(try | |
(set! *iderefs* (conj *iderefs* o)) | |
(catch IllegalStateException e)) | |
(print-sequential (format "#<%s@%x: " | |
(.getSimpleName (class o)) | |
(System/identityHashCode o)) | |
pr-on, "", ">", (list @o), w)))) | |
user=> (binding [*iderefs* #{}] | |
(let [a (atom :a) | |
b (atom :b)] | |
(reset! b a) | |
(reset! a b) | |
(prn [a b]))) | |
[#<Atom@78467991: #<Atom@5ad75c47: #<Atom@78467991>>> #<Atom@5ad75c47>] | |
nil |
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