使用包装阴影符号 [英] Use package shadowing symbols

问题描述

例如，我有这个包定义，它笼罩着COMMON-LISP:LISTEN:

For instance I have this package definition which shadows COMMON-LISP:LISTEN :

(defpackage :shadows
  (:use :common-lisp)
  (:shadow #:listen)
  (:export #:listen))

然后我想从另一个软件包中使用这个软件包，例如

And then I want to use this package from another package, say

(defpackage :light
  (:use :common-lisp
        :shadows))

如果在使用该软件包时实际上无法覆盖Common Lisp符号，那么阴影的作用是什么?

What is the purpose of shadow if I cannot actually override Common Lisp symbols when using the package ?

推荐答案

好的，因此实际上有一种方便的方法.

OK so there actually is a handy way to do this.

在多阴影包中，我导出了shadowing-import-from函数.看起来像这样:

In my many-shadows package I export a shadowing-import-from function. It looks like this :

(defun shadowing-import-from ()
  `(:shadowing-import-from :many-shadows
     ,@(package-shadowing-symbols :many-shadows)))

然后，在轻量的defpackage中，我只是对其进行READ-EVAL评估:

And then, in the light defpackage I just READ-EVAL it :

(defpackage :light
  (:use :common-lisp
        :many-shadows)
  #.(many-shadows:shadowing-import-from))

因此，很明显，有些东西被遮盖了，我想优先使用来自许多阴影的符号.而且它足够短，可以被实用地记录和使用.

So it is explicit that something was shadowed and that I want to use the symbols from many-shadows in priority. And it is short enough to be documented and used pragmatically.

感谢@sds将我指向:shadowing-import-from.

Thank you @sds for pointing me to :shadowing-import-from.

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