store/[org.clojure/clojure "1.8.0"] clj::clojure.core/remove-all-methods

Official Documentation

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Arities
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   [multifn]

Docstring
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  Removes all of the methods of multimethod.

Source

(defn remove-all-methods
  "Removes all of the methods of multimethod."
  {:added "1.2"
   :static true} 
 [^clojure.lang.MultiFn multifn]
 (.reset multifn))

Example 1

Edit
;; example showing use of multi-methods before and after remove-all-methods
;; after removing all the methods, both circle and line tos functions throw
;; exceptions

(defmulti tos :Ob)
;; => nil

(defn line [p1 p2] {:Ob :line :p1 p1 :p2 p2})
;; => #'user/line

(defn circle [cent rad] {:Ob :circle :cent cent :rad rad})
;; => #'user/circle

(defmethod tos :line [l] (str "Line:" (l :p1) (l :p2)))
;; => #<MultiFn clojure.lang.MultiFn@73aecc3a>

(defmethod tos :circle [c] (str "Circle:" (c :cent) (c :rad)))
;; => #<MultiFn clojure.lang.MultiFn@73aecc3a>

(println (tos (circle [2 3] 3.3)))
;; > Circle:[2 3]3.3
;; => nil

(println (tos (line [1 1] [0 0])))
;; > Line:[1 1][0 0]
;; => nil

(remove-all-methods tos)
;; => #<MultiFn clojure.lang.MultiFn@73aecc3a>

(println (tos (circle [2 3] 3.3)))
;; > java.lang.IllegalArgumentException: No method in multimethod 'tos' for dispatch
;; => value: :circle (NO_SOURCE_FILE:0)

(println (tos (line [1 1] [0 0])))
;; > java.lang.IllegalArgumentException: No method in multimethod 'tos' for dispatch
;; => value: :line (NO_SOURCE_FILE:0)

Uses on crossclj