diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/clj/clojure/core_deftype.clj | 51 |
1 files changed, 50 insertions, 1 deletions
diff --git a/src/clj/clojure/core_deftype.clj b/src/clj/clojure/core_deftype.clj index 6f727885..85f3b422 100644 --- a/src/clj/clojure/core_deftype.clj +++ b/src/clj/clojure/core_deftype.clj @@ -374,7 +374,7 @@ If you are supplying the definitions explicitly (i.e. not reusing exsting functions or mixin maps), you may find it more convenient to - use the extend-type and extend-class macros. + use the extend-type, extend-class or extend-protocol macros. Note that multiple independent extend clauses can exist for the same type, not all protocols need be defined in a single extend call. @@ -449,3 +449,52 @@ all fns" [c & specs] (emit-extend-class c specs)) + +(defn- emit-extend-protocol [p specs] + (let [impls (parse-impls specs)] + `(do + ~@(map (fn [[t fs]] + (if (symbol? t) + `(extend-class ~t ~p ~@fs) + `(extend-type ~t ~p ~@fs))) + impls)))) + +(defmacro extend-protocol + "Useful when you want to provide several implementations of the same + protocol all at once. Takes a single protocol and the implementation + of that protocol for one or more types. Expands into calls to + extend-type and extend-class: + + (extend-protocol Protocol + ::AType + (foo [x] ...) + (bar [x y] ...) + ::BType + (foo [x] ...) + (bar [x y] ...) + AClass + (foo [x] ...) + (bar [x y] ...) + nil + (foo [x] ...) + (bar [x y] ...)) + + expands into: + + (do + (clojure.core/extend-type ::AType Protocol + (foo [x] ...) + (bar [x y] ...)) + (clojure.core/extend-type ::BType Protocol + (foo [x] ...) + (bar [x y] ...)) + (clojure.core/extend-class AClass Protocol + (foo [x] ...) + (bar [x y] ...)) + (clojure.core/extend-type nil Protocol + (foo [x] ...) + (bar [x y] ...)))" + + [p & specs] + (emit-extend-protocol p specs)) + |