* About `current-directory-list'
@ 2012-12-23 1:58 Xue Fuqiao
2012-12-23 2:25 ` Drew Adams
0 siblings, 1 reply; 3+ messages in thread
From: Xue Fuqiao @ 2012-12-23 1:58 UTC (permalink / raw)
To: help-gnu-emacs
[-- Attachment #1: Type: text/plain, Size: 571 bytes --]
In node 14.9.2 of Bob's `An Introduction to Programming in Emacs Lisp'(http://www.gnu.org/software/emacs/emacs-lisp-intro/html_node/Files-List.html#Files-List), there is a function called `files-in-below-directory' that lists the .el files in a directory and its subdirs.
The varlist of the `let' special form is:
(el-files-list
(current-directory-list
(directory-files-and-attributes directory t)))
I don't know what does `current-directory-list' means, in my Emacs(24.2), there isn't a function named `current-directory-list'. Can anybody help?
--
Best regards.
[-- Attachment #2: filelist.el --]
[-- Type: application/octet-stream, Size: 1715 bytes --]
(defun files-in-below-directory (directory)
"List the .el files in DIRECTORY and in its sub-directories."
;; Although the function will be used non-interactively,
;; it will be easier to test if we make it interactive.
;; The directory will have a name such as
;; "/usr/local/share/emacs/22.1.1/lisp/"
(interactive "DDirectory name: ")
(let (el-files-list
(current-directory-list
(directory-files-and-attributes directory t)))
;; while we are in the current directory
(while current-directory-list
(cond
;; check to see whether filename ends in `.el'
;; and if so, append its name to a list.
((equal ".el" (substring (car (car current-directory-list)) -3))
(setq el-files-list
(cons (car (car current-directory-list)) el-files-list)))
;; check whether filename is that of a directory
((eq t (car (cdr (car current-directory-list))))
;; decide whether to skip or recurse
(if
(equal "."
(substring (car (car current-directory-list)) -1))
;; then do nothing since filename is that of
;; current directory or parent, "." or ".."
()
;; else descend into the directory and repeat the process
(setq el-files-list
(append
(files-in-below-directory
(car (car current-directory-list)))
el-files-list)))))
;; move to the next filename in the list; this also
;; shortens the list so the while loop eventually comes to an end
(setq current-directory-list (cdr current-directory-list)))
;; return the filenames
el-files-list))
^ permalink raw reply [flat|nested] 3+ messages in thread* RE: About `current-directory-list'
2012-12-23 1:58 About `current-directory-list' Xue Fuqiao
@ 2012-12-23 2:25 ` Drew Adams
2012-12-23 2:42 ` Xue Fuqiao
0 siblings, 1 reply; 3+ messages in thread
From: Drew Adams @ 2012-12-23 2:25 UTC (permalink / raw)
To: 'Xue Fuqiao', help-gnu-emacs
> The varlist of the `let' special form is:
> (el-files-list
> (current-directory-list
> (directory-files-and-attributes directory t)))
>
> I don't know what does `current-directory-list' means, in my
> Emacs(24.2), there isn't a function named
> `current-directory-list'. Can anybody help?
It is a local variable bound in that `let'. You show two bindings:
1. `el-files-list' is bound to nil (implicitly).
2. `current-directory-list' is bound to (directory-files-and...).
I, for one, prefer to write any implicit bindings last, after the explicit ones:
(let ((current-directory-list (directory-files-...))
el-files-list)
I think that is more readable. And if I want to draw attention to an initial
value of nil then I use an explicit binding. And if it is a list variable then
I use (); if a Boolean or other I use nil. E.g.:
(let ((el-files-list ())
(found nil))
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2012-12-23 2:42 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2012-12-23 1:58 About `current-directory-list' Xue Fuqiao
2012-12-23 2:25 ` Drew Adams
2012-12-23 2:42 ` Xue Fuqiao
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).