我刚刚编写了我一生中最荒谬的宏来支持这个功能。可能有一种更简单的方法——如果我能想到一个，我一定会发布它——但这给了我一种很酷、很迷幻的感觉，而且实际上似乎很有效，所以……就这样吧。
编辑：这是一个更简单的方法；定义一个返回常规 proxy 的函数，它委托所有方法（手动编写或自动创建它 - delegating-proxy 的代码包含这样做的方法），在单个实例上使用 update-proxy 来替换需要更换的方法。这显然没有疯狂的宏那么酷，所以后者将保持在下面。
这是新的简化方法（由于位置参数计数限制和可变参数的一些问题，仍然不是很清楚）：
;;; delegates all methods
(defmacro delegating-proxy [o class-and-ifaces ctor-args]
(let [oname (gensym)
impls (->> class-and-ifaces
(map resolve)
(mapcat #(.getDeclaredMethods ^Class %))
(group-by #(.getName ^java.lang.reflect.Method %))
(vals)
(map (fn delegating-impls [^java.lang.reflect.Method ms]
(let [mname (symbol (.getName ^java.lang.reflect.Method (first ms)))
arity-groups (partition-by #(count (.getParameterTypes ^java.lang.reflect.Method %)) ms)
max-arity (max-key #(count (.getParameterTypes ^java.lang.reflect.Method %)) ms)]
`(~mname
~@(remove
nil?
(map (fn [agroup]
(let [param-types (.getParameterTypes ^java.lang.reflect.Method (first agroup))
vararg? (and (seq param-types) (or (.isArray ^Class (last param-types)) (<= 20 (count param-types))))
arity ((if vararg? dec identity) (count param-types))
params (vec (repeatedly arity gensym))
params (if vararg? (conj params '& (gensym)) params)]
(when-not (and vararg? (not= arity max-arity))
(list params `(. ~oname (~mname ~@params))))))
arity-groups)))))))]
`(let [~oname ~o]
(proxy ~class-and-ifaces ~ctor-args ~@impls))))
一个演示：
user> (def p (delegating-proxy (fn [& args] :foo) [clojure.lang.IFn] []))
#'user/p
user> (update-proxy p {"applyTo" (fn [& args] :bar)})
#<Object$IFn$4c646ebb user.proxy$java.lang.Object$IFn$4c646ebb@1c445f88>
user> (p 1)
:foo
user> (apply p (seq [1]))
:bar
编辑：原始宏如下。
首先，一个演示：
user> (.invoke (delegating-proxy (fn [x y] (prn x y))
[clojure.lang.IFn] []
(invoke [x] :foo))
:bar)
:foo
user> (.invoke (delegating-proxy (fn [x y] (prn x y))
[clojure.lang.IFn] []
(invoke [x] :foo))
:bar :quux)
:bar :quux
nil
delegating-proxy 接受一个对象，当被调用以执行未显式实现的方法时，该对象委托给该对象，后跟常规 proxy 参数。
第二，代码。我认为可以肯定地假设其中潜伏着各种缺陷。实际上它的一般形状就在那里。没有潜伏。如果它对某人足够有用，它可能会被测试并改进为某种程度的可靠稳健性。
The Gist 更容易阅读。
(defmacro delegating-proxy [o class-and-ifaces ctor-args & impls]
(let [oname (gensym)]
(letfn [(delegating-impls [^java.lang.reflect.Method ms]
(let [mname (symbol (.getName ^java.lang.reflect.Method (first ms)))
arity-groups (partition-by #(count (.getParameterTypes ^java.lang.reflect.Method %)) ms)
max-arity (max-key #(count (.getParameterTypes ^java.lang.reflect.Method %)) ms)]
`(~mname
~@(remove
nil?
(map (fn [agroup]
(let [param-types (.getParameterTypes ^java.lang.reflect.Method (first agroup))
vararg? (and (seq param-types) (or (.isArray ^Class (last param-types)) (<= 20 (count param-types))))
arity ((if vararg? dec identity) (count param-types))
params (vec (repeatedly arity gensym))
params (if vararg? (conj params '& (gensym)) params)]
(when-not (and vararg? (not= arity max-arity))
(list params `(. ~oname (~mname ~@params))))))
arity-groups)))))
(combine-impls [eimpls dimpls]
(map (fn [e d]
(let [e (if (vector? (second e))
(list (first e) (next e))
e)]
(list* (first e) (concat (next e) (next d)))))
eimpls
dimpls))]
(let [klass (resolve (first class-and-ifaces))
methods (->> class-and-ifaces
(map resolve)
(mapcat #(.getDeclaredMethods ^Class %)))
eimpl-specs (set (map (juxt first (comp count second)) impls))
rm-fn (fn rm-fn [^java.lang.reflect.Method m]
(contains? eimpl-specs [(symbol (.getName m)) (count (.getParameterTypes m))]))
dimpls (->> methods
(remove rm-fn)
(remove #(let [mods (.getModifiers ^java.lang.reflect.Method %)]
(or (java.lang.reflect.Modifier/isPrivate mods)
(java.lang.reflect.Modifier/isProtected mods))))
(sort-by #(.getName ^java.lang.reflect.Method %))
(partition-by #(.getName ^java.lang.reflect.Method %))
(map delegating-impls))
dimpl-names (set (map first dimpls))
eimpl-names (set (map first eimpl-specs))
{eonly false eboth true} (group-by (comp boolean dimpl-names first) impls)
{donly false dboth true} (group-by (comp boolean eimpl-names first) dimpls)
all-impls (concat eonly donly (combine-impls eboth dboth))]
`(let [~oname ~o]
(proxy ~class-and-ifaces ~ctor-args
~@all-impls))))))