带有前缀参数和用户输入作为可选参数的 ELISP 交互函数

Question

在 ELISP 中，interactive codes 的文档提到：

P -- Prefix arg in raw form. Does not do I/O. ... s -- Arbitrary text, read in the minibuffer and returned as a string ... Prompt.

我假设我可以编写一个带有可选前缀参数的函数，如：

(defun some-function (&optional prefix)
    (interactive "P")
    ...
)

或带有用户输入的函数，如：

(defun some-function (user-argument)
  (interactive "sProvide an argument: ")
  ...
)

但不是两者。然后我找到了 Org-mode 函数 org-match-sparse-tree，我可以用 C-u C-c \ 调用它，其中前缀参数限制匹配打开 org-mode 标题，我仍然提示匹配.源代码在下面，我找不到变量 match 是如何赋值的：

(defun org-match-sparse-tree (&optional todo-only match)
  "..."
  (interactive "P")
  (org-agenda-prepare-buffers (list (current-buffer)))
  (let ((org--matcher-tags-todo-only todo-only))
    (org-scan-tags 'sparse-tree (cdr (org-make-tags-matcher match))
           org--matcher-tags-todo-only)))

此函数如何同时接受前缀参数和用户输入？

Answer 1

How does this function [interactively] take both prefix argument and user input?

它不是 -- match 参数未获得，因此是 nil。您看到的是随后以 nil 值作为参数调用 (org-make-tags-matcher match) 的效果：

(defun org-make-tags-matcher (match)
  "..."
  (unless match
    ;; Get a new match request, with completion against the global
    ;; tags table and the local tags in current buffer.
    (let ((org-last-tags-completion-table
           (org-tag-add-to-alist
            (org-get-buffer-tags)
            (org-global-tags-completion-table))))
      (setq match
            (completing-read
             "Match: "
             'org-tags-completion-function nil nil nil 'org-tags-history))))
  ...)

函数可以接受多个interactive参数。

参见C-hf interactive

To pass several arguments to the command, concatenate the individual strings, separating them by newline characters.

该帮助中的第一个示例说明了这一点：

(defun foo (arg buf) "Doc string" (interactive "P\nbbuffer: ") .... )

这在 (elisp)Using Interactive 中进行了详细说明 -- 您链接到的文档中的上一级：

It may be a string; its contents are a sequence of elements
separated by newlines, one for each argument(1).  Each element
consists of a code character (*note Interactive Codes::) optionally
followed by a prompt (which some code characters use and some
ignore).  Here is an example:

     (interactive "P\nbFrobnicate buffer: ")

The code letter ‘P’ sets the command’s first argument to the raw
command prefix (*note Prefix Command Arguments::).  ‘bFrobnicate
buffer: ’ prompts the user with ‘Frobnicate buffer: ’ to enter the
name of an existing buffer, which becomes the second and final
argument.

不过，您应该完整阅读该文档——您可以做更复杂的事情，包括编写任意 elisp 来生成交互式参数（这可能涉及也可能不涉及提示用户）。

带有前缀参数和用户输入作为可选参数的 ELISP 交互函数

ELISP interactive function with both prefix argument and user input as optional arguments

function

arguments

lisp

elisp

optional