目前，我正在使用load-history变量来查找一个功能所在的文件。
假设要查找功能gnus所在的文件。
我在scratch缓冲区中执行以下代码，可以按顺序打印文件名和符号：
(dolist (var load-history)
(princ (format "%s\n" (car var)))
(princ (format "\t%s\n" (cdr var))))
然后搜索“(provide . gnus)”并将光标移至该行的开头（Ctrl+A）。前一行中的文件名是该功能所属的文件。
这种方法有什么问题吗，或者是否存在更好的方法。
你的方法很好。任何一种解决问题的方法都是好的。
@Tom是正确的，你不应该需要这样做，因为帮助系统已经为你解决了问题。也就是说，C-h f
但那没什么意思。假设你真的想要一个自动的、更优雅的解决方案。你需要一个函数--locate-feature，其签名如下:
(defun locate-feature (feature)
"Return file-name as string where `feature' was provided"
...)
load-history 方式You've already got the most important part -- find the variable with the information you need.
I notice immediately that this variable has a lot of data. If I insert it into a buffer as a single line, Emacs will not be happy, because it's notoriously bad at handling long lines. I know that the prett-print package will be able to format this data nicely. So I open up my *scratch* buffer and run
M-: (insert (pp-to-string load-history))
I can now see the data structure I'm dealing with. It seems to be (in pseudo code):
((file-name
((defun|t|provide . symbol)|symbol)*)
...)
Now I just write the function
(eval-when-compile (require 'cl))
(defun locate-feature (feature)
"Return file name as string where `feature' was provided"
(interactive "Sfeature: ")
(dolist (file-info load-history)
(mapc (lambda (element)
(when (and (consp element)
(eq (car element) 'provide)
(eq (cdr element) feature))
(when (called-interactively-p 'any)
(message "%s defined in %s" feature (car file-info)))
(return (car file-info))))
(cdr file-info))))
The code here is pretty straight forward. Ask Emacs about the functions you don't understand.
方法一适用于特性。但是如果我想知道任何可用函数的定义在哪里呢？不仅仅是特性。
C-h f 已经告诉了我，但我想要一个包含文件名的字符串，而不是所有冗长的帮助文本。我想要这个：
(defun locate-function (func)
"Return file-name as string where `func' was defined or will be autoloaded"
...)
让我们开始吧。
C-h f is my starting point, but I really want to read the code that defines describe-function. I do this:
C-h k C-h f C-x o tab enter
Now I'm in help-fns.el at the definition of describe-function. I want to work only with this function definition. So narrowing is in order:
C-x n d
I have a hunch that the interesting command will have "find" or "locate" in its name, so I use occur to search for interesting lines:
M-s o find\|locate
No matches. Hmmm. Not a lot of lines in this defun. describe-function-1 seems to be doing the real work, so we try that.
I can visit the definition of describe-function-1 via C-h f. But I already have the file open. imenu is available now:
C-x n w M-x imenu desc*1 tab enter
Narrow and search again:
C-x n d M-s o up enter
I see find-lisp-object-file-name which looks promising.
After reading C-h f find-lisp-object-file-name I come up with:
(defun locate-function (func)
"Return file-name as string where `func' was defined or will be autoloaded"
(interactive "Ccommand: ")
(let ((res (find-lisp-object-file-name func (symbol-function func))))
(when (called-interactively-p 'any)
(message "%s defined in %s" func res))
res))
只需使用symbol-file命令。它会扫描格式为load-history的文件：
Each entry has the form `(provide . FEATURE)',
`(require . FEATURE)', `(defun . FUNCTION)', `(autoload . SYMBOL)',
`(defface . SYMBOL)', or `(t . SYMBOL)'. Entries like `(t . SYMBOL)'
may precede a `(defun . FUNCTION)' entry, and means that SYMBOL was an
autoload before this file redefined it as a function. In addition,
entries may also be single symbols, which means that SYMBOL was
defined by `defvar' or `defconst'.
(symbol-file 'scheme 'provide) ; Who provide feature.
(symbol-file 'nxml-mode-hook 'defvar) ; Where variable defined.
(symbol-file 'message-send 'defun) ; Where function defined.
(symbol-file 'scheme) ; Look for symbol despite its type.
有一个locate-library可以帮助你。
试试下面的代码...
M-: (locate-library "my-feature")
例如：(locate-library "gnus")
locate-library 根据文件名进行定位。虽然大多数情况下每个文件只提供一个功能，并且该功能以文件命名，但这两件事情都不一定是真实的。 - event_jr这并没有什么问题，但为什么它比获取关键字或函数的帮助更简单呢？例如，如果您使用gnus命令，并想知道它来自哪里，那么您可以使用C-h k，它会告诉您它的定义来自哪个elisp文件。
(symbol-file 'gnus)。第二个参数可以是defun/defvar/defface。 - gavenkoa