function - 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 的文档提及:

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，如下所示:

(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: ")
  ...
)

但不是两者兼而有之。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，其中前缀参数将匹配限制为打开 org-模式标题，我仍然被提示匹配。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)))

这个函数如何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，因此为 nil。您看到的是随后调用 (org-make-tags-matcher match) 的效果，该 nil 值作为参数:

(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))))
  ...)

---

不过，函数可以采用多个交互式参数。

参见 C-hf 交互式

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演示了这一点:

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

这在 (elisp)Using Interactive 中进行了详细说明——在您链接到的文档中上一级:

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)。