GNU bug report logs - #1939
suggestion: adding read-line function to elisp

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Message #5 received at submit <at> emacsbugs.donarmstrong.com (full text, mbox):

From: xah lee <xah <at> xahlee.org>
To: bug-gnu-emacs <at> gnu.org
Subject: suggestion: adding read-line function to elisp
Date: Sat, 17 Jan 2009 10:13:51 -0800

summary:
i'd like to have a  read-line function in elisp, that will read a  
given file and return a list of lines.

The reason is that in almost all modern scripting langs (php, perl,  
python, ruby), there's such a function, so that users can get a list  
of lines of a file in about single line of code. Getting lines as  
list is a very frequent need.

elisp is very suitable for tasks of text processing. So, having such  
a convenience function seems appropriate.

Here's a implementation:

(defun read-lines (file)
  "Return a list of lines in FILE."
  (with-temp-buffer
    (insert-file-contents file)
    (split-string
     (buffer-substring-no-properties 1 (point-max)) "\n" t)
    )
  )

Thanks.

The thought came from a recent newsgroup discussion in comp.lang.lisp
http://groups.google.com/group/comp.lang.lisp/browse_frm/thread/ 
761fe827c8c9ea5e/

Here's a short article for some context:

• A Ruby Illustration of Lisp Problems
  http://xahlee.org/UnixResource_dir/writ/lisp_problems_by_ruby.html

  Xah
∑ http://xahlee.org/

☄

Message #10 received at 1939 <at> emacsbugs.donarmstrong.com (full text, mbox):

From: Juanma Barranquero <lekktu <at> gmail.com>
To: xah lee <xah <at> xahlee.org>
Cc: 1939 <at> debbugs.gnu.org
Subject: Re: bug#1939: suggestion: adding read-line function to elisp
Date: Sun, 18 Jan 2009 06:48:10 +0100

On Sat, Jan 17, 2009 at 19:13, xah lee <xah <at> xahlee.org> wrote:

> Getting lines as list is a very frequent need.
>
> elisp is very suitable for tasks of text processing. So, having such a
> convenience function seems appropriate.

Getting lines as list is much less frequent in elisp. The reason is
that is much more flexible (and faster) to manipulate text in a buffer
than as a collection of strings.

So in most cases, using `with-temp-buffer' (as in your read-lines
function) is the Right Thing To Do.

    Juanma

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