适用于具有各种数据字段的用户的功能 [英] Function for applying to a user with a various number of data fields

问题描述

当我练习教程
我正在尝试将该功能应用于用户，但无法使用用户的数据字段（例如姓名，姓氏）。

The question was born when I was practicing an Observer topic in a tutorial I am trying to apply the function to the user but cannot use user's data fields like name, surname.

假设用户可能具有不同数量的数据字段，因此我们必须使用& args 参数。我的代码无效：

Let's say that the user may have various number of data fields so we must use & args argument. My code that does not work:

(ns observer.core)
(def user {:name "Alan" :surname "Smith" :alias "Mike"})
(def user2 {:name "Jane" :surname "Smith"})
(apply
 (fn [& args] (println (str "I am " (:name args) " " (:surname args) ".")))
   user)
(apply
 (fn [& args] (println (str "My sister is " (:name args) " " (:surname args) ".")))
   user2)

输出：

I am  .
My sister is  .
observer.core> 

如何解决应用

推荐答案

apply 将映射转换为seq ，即
{：name Alan：surname Smith：alias Mike} 变成（[：name Alan ] [：姓氏 Smith] [：别名 Mike]）

apply converts a map to a seq, i.e. {:name "Alan" :surname "Smith" :alias "Mike"} becomes ([:name "Alan"] [:surname "Smith"] [:alias "Mike"])

如果可以，可以将其放回地图中您需要什么：

You could put it back into a map, if that is what you need:

(let [user {:name "Alan" :surname "Smith" :alias "Mike"}]
    (apply
        (fn [& args]
            (let [args (into {} args)]
                (println (str "I am " (:name args) " " (:surname args) "."))))
        user))

但是这对我来说似乎有点困难。我相信，如果我知道应该如何使用此功能，解决方案可能会更好。

but this looks a bit of a stretch to me. I believe the solution could have been better if I knew how this function is supposed to be used.

通常有两种类型的功能：（ fn：text some：row 25）和（fn {：text some：row 25}）。

Usually there are two types of functions: (fn :text "some" :row 25) and (fn {:text "some" :row 25}).

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