Clojure + Clojurescript：宏读取当前文件的代码 [英] Clojure + Clojurescript: Macro to read code of current file

问题描述

(defmacro magic []
  (slurp *file*))

这在clojure中可以正常工作，但不能在clojurescript中使用（至少不使用lein figwheel）。

This works fine in clojure, but not in clojurescript (atleast not with lein figwheel).

我需要以下工作在Clojure和Clojurescript。我认为宏是正确的解决方案，但我对其他技术开放。

I need the following to work in both Clojure and Clojurescript. I think a macro is the right solution, but I'm open to other techniques.

我想要一种方式读取当前文件一个字符串。例如：

I want a way to read the current file as a string. For example,

(ns my-test
  (:require blah))

(def foo 20)

(println (blah/magic))

这应该会导致（打印输出）

this should then result in (being printed out)

(ns my-test
  (:require blah))

(def foo 20)

(println (blah/magic))

如果我只需要在Clojure工作，我可以做有趣的事情与当前文件，并在运行时读取它。但是，我需要这也工作在Clojurescript（我不想设置一些REST API提供* .cljs文件） - 因此，有一些方法在编译时通过一些宏？

If I only needed this to work in Clojure, I could do funny things with the current file and reading it at run time. However, I need this also to work in Clojurescript (and I don't want to setup some REST API to serve *.cljs files) -- thus, is there some way to do this at compile time via some macro?

假设你想写一个cheating quine，你会怎么做？可能是像（println（slurp * file *））。现在，有什么问题？

Suppose you wanted to write a "cheating quine" -- how would you do it? Probably something like (println (slurp *file*)). Now, what's the problem? This doesn't work in clojurescript when running under lein figwheel.

推荐答案

您需要阅读条件，如下：

You need Reader Conditionals like this:

(defn build-list []
  (list #?@(:clj  [5 6 7 8]
            :cljs [1 2 3 4])))

请参阅此处的文档：

http://clojure.org/guides/reader_conditionals

https://github.com/clojure / clojurescript / wiki / Using-cljc

UPDATE 1

如果要修改当前执行的源代码，您可以始终构造一个字符串并使用 eval ：

If you want to modify the currently executing source code, you can always construct a string and use eval:

(eval (read-string "(defn darth [] (println \"I have the ultimate power now...\" ))" ))

(darth)
;=> I have the ultimate power now...

但是，由于ClojureScript是编译的，我不认为

However, since ClojureScript is compiled, I don't think there is any simple way of finding the source original source code, if that's what you're after.

UPDATE 2

这是一个有趣的问题。最近我来的是这样的：

It's an interesting problem. The closest I've come so are is something like this:

(ns clj.core)

(defmacro fred [& forms]
  (doseq [f forms]
    (println `~f)))

(fred 
  (+ 1 2)
  (* 2 3)
)

(defn -main [& args])

结果：

> lein run    
(+ 1 2)
(* 2 3)

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