elisp-获取相对于脚本的文件路径

Question

Say I am writing an emacs lisp function that interfaces with a file located relative to the file in which the function is defined.

- bin/executable
- foo.el

foo.el :

(defun foo ()
  (shell-command-to-string
   (format "echo '%s' | ./bin/executable"
           (buffer-substring-no-properties
            (point-min)
            (point-max)))))

If I run this from foo.el then it works great. If I invoke the function while editing any other file it doesn't work because the path ain't right.

How can I reliably reference ./bin/executable from within foo.el no matter where the function is invoked?

Answer 1

Use load-file-name variable.

(defconst directory-of-foo (file-name-directory load-file-name))

(defun foo ()
  (shell-command-to-string
   (format "echo '%s' | %s"
           (buffer-substring-no-properties
            (point-min)
            (point-max))
           (expand-file-name "./bin/executable" directory-of-foo))))

Answer 2

You can use a combination of load-file-name and default-directory . If you only check the former, the file will work if you explicitly load it, but it will not work if you eval it in a buffer.

For example:

(defvar my-directory (if load-file-name
                         ;; File is being loaded.
                         (file-name-directory load-file-name)
                       ;; File is being evaluated using, for example, `eval-buffer'.
                       default-directory))

In addition, it might be a good idea to convert the path to an absolute path using expand-file-name .