问题描述
在Clojure中，如果我有一个函数f，
In Clojure, if I have a function f,
(defn f [& r] ... )
并且我有一个 seq args 带有我想调用 f 的参数，我可以轻松地使用 apply:
and I have a seq args with the arguments I want to call f with, I can easily use apply:
(apply f args)
现在，假设我有另一个函数 g，它被设计为采用许多可选的命名参数中的任何一个 - 也就是说，其余参数被解构为映射:
Now, say I have another function g, which is designed to take any of a number of optional, named arguments - that is, where the rest argument is destructured as a map:
(defn g [& {:keys [a b] :as m}] ... )
我通常会通过做类似的事情来调用 g
I'd normally call g by doing something like
(g :a 1 :b 2)
但是如果我碰巧有一个值为 {:a 1 :b 2} 的地图 my-map，并且我想将 g应用"到我的地图 - 换句话说，得到一些最终会作为上述调用的东西，那么我自然不能使用apply，因为它相当于
but if I happen to have a map my-map with the value {:a 1 :b 2}, and I want to "apply" g to my-map - in other words, get something that would end up as the above call, then I naturally couldn't use apply, since it would be equivalent to
(g [:a 1] [:b 2])
有什么好的方法可以解决这个问题吗?我可能会在我的设计中偏离轨道以结束这个吗?我能找到的最佳解决方案是
Is there a nice way to handle this? May I have gone off track in my design to end up with this? The best solution I can find would be
(apply g (flatten (seq my-map)))
但我肯定不喜欢它.有什么更好的解决方案吗?
but I surely don't like it. Any better solutions?
对建议的解决方案的轻微改进可能是
A slight improvement to the suggested solution might be
(apply g (mapcat seq my-map))
这至少删除了一个函数调用，但可能仍然不是很清楚发生了什么.
which at least removes one function call, but it may still not be very clear what's going on.
推荐答案
我自己偶然发现了这个问题，最终定义了期望一张地图的函数.一个映射可以有可变数量的键/值对，如果足够灵活，那么就不需要 &休息论据.申请也没有痛苦.让生活更轻松！
I have stumbled into this problem myself and ended up defining functions to expect one map. A map can have a variable amount of key/value pairs, and if flexible enough, so there is no need for & rest arguments. Also there is no pain with apply. Makes life a lot easier!
(defn g [{:keys [a b] :as m}] ... )
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