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Re: About `constrain-to-field'
From: |
Xue Fuqiao |
Subject: |
Re: About `constrain-to-field' |
Date: |
Tue, 19 Mar 2013 07:16:03 +0800 |
On Mon, 18 Mar 2013 19:36:56 +0200
Eli Zaretskii <eliz@gnu.org> wrote:
> > I have read (info "(elisp) Fields") and doc string of the function
> > `constrain-to-field', but I cannot understand what this function does,
> > especially for its optional arguments.
> I suggest to grep the Emacs Lisp sources, there are several examples
> there.
Thanks. It is used in paragraphs.el, simple.el and comint.el. I have read
the definition for `delete-horizontal-space', because it is not very
complex (comparing with `next-line') and it is written in Lisp
(comparing to `beginning-of-line').
But the sexp `(constrain-to-field nil orig-pos t)' is the only
expression I don't understand in this function. Is there any relation
between field and whitespace?
> As for the documentation, the manual sounds very clear to me, so I
> suggest to ask specific questions about the parts that confuse you.
I did some experiments. I used this function with or without optional
arguments to a range of consecutive characters in the buffer that are
identified by having the same value of the `field' property. But
whether they are in the same line or not, the value returned is always
equal to OLD-POS.
--
Xue Fuqiao
http://www.gnu.org/software/emacs/