应该用`cl-flet`或`cl-letf`代替`flet`？ [英] Should `flet` be replaced with `cl-flet` or `cl-letf` ?

问题描述

我安装的一些elisp函数生成警告：

Some elisp functions that I have installed generate warnings:

`flet' is an obsolete macro (as of 24.3); use either `cl-flet' or `cl-letf'.

如果我只是将所有 flet 与 cl-flet ？
如果可以替换它们，哪一个更好？

Is it dangerous if I simply replace all flet with cl-flet? If it is OK to replace them, which one is better?

如果更换它不是危险的，我会将拉请求发送到项目

If it is not dangerous to replace it, I'd send pull requests to the projects.

有没有理由不改变它？

推荐答案

flet 与 cl-flet 或 cl-letf不同。
这更危险（也许更强大）。这就是为什么它被废弃了。

flet isn't the same as either cl-flet or cl-letf. It's more dangerous (and maybe more powerful). That's why it's being deprecated.

由于它是不同的（动态绑定一个函数名称），你必须考虑
在每种情况下，如果适合替换它 cl-flet 。

Since it's different (binds dynamically a function name), you have to think in each case if it's appropriate to replace it with cl-flet.

(defun adder (a b)
  (+ a b))

(defun add-bunch (&rest lst)
  (reduce #'adder lst))

(add-bunch 1 2 3 4)
;; 10

(flet ((adder (a b) (* a b)))
  (add-bunch 1 2 3 4))
;; 24

(cl-flet ((adder (a b) (* a b)))
  (add-bunch 1 2 3 4))
;; 10

请注意， cl-flet 绑定，所以加法器的行为没有改变，
而 flet 做动态绑定 add-bunch 暂时产生阶乘。

Note that cl-flet does lexical binding, so the behavior of adder isn't changed, while flet does dynamic binding, which makes add-bunch temporarily produce a factorial.

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