如何自动创建Clojure`defn`函数? [英] How to Create Clojure `defn` Functions automatically?

问题描述

我重新编写了此代码，以使原来的问题更清晰，并添加了全宏解决方案.请忽略此版本，并参考以下内容:

I re-wrote this to make the original problem clearer and added the all-macro solution. Please ignore this version and refer to the following:

如何在不使用宏的情况下自动创建Clojure`defn`函数?

很遗憾，SO不允许我删除此旧版本.

Unfortunately, SO will not allow me to delete this older version.

最初由以下问题引起:映射到clojurescript宏的调用

Originally motivated by the following question: Mapped calls to clojurescript macro

假设您要自动创建许多相似的功能(即无需全部手写).假设我们有一些预先存在的数据，并且我们想要编写访问器函数，如下所示:

Suppose you want to create many similar functions automatically (i.e. without hand-writing them all). Suppose we have some pre-existing data and we want to write accessor functions like so:

(def foo
  {:able    "Adelicious!"
   :baker   "Barbrallicious!"
   :charlie "Charlizable"})
(def bar
  {:able    "Apple"
   :baker   "Berry"
   :charlie "Kumquat"})

(defn manual-my-foo [item] (get foo item))
(defn manual-my-bar [item] (get bar item))

(manual-my-foo :able) => "Adelicious!"
(manual-my-bar :charlie) => "Kumquat"

因此manual-my-foo是硬接线"的，以使用foo全局地图.

So manual-my-foo is "hard-wired" to use the foo global map.

您可能会认为需要一个宏来创建此功能，这是一种解决方案.但是，宏的缺点是不能将它们作为参数传递给另一个函数，例如map.因此，我们可以编写一个像这样的宏:

You might think you need a macro to create this function, and that is one solution. However, a weakness of macros is that they cannot be passed as arguments to another function such as map. Thus, we could write a macro like:

(generate-fn :foo)  ;=> creates `my-foo` w/o hand-writing it

，但以下操作将失败:

(map generate-fn [:foo :bar :baz])  

我们如何自动生成这些功能?

How can we automate the generation of these functions?

推荐答案

我们如何自动生成这些功能?

How can we automate the generation of these functions?

您不需要. foo和bar映射可按您期望的功能运行:

You don't need to. The foo and bar maps operate as the functions you desire:

(foo :able) ; "Adelicious!"

(bar :able) ; "Apple"

这篇关于如何自动创建Clojure`defn`函数?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！