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Re: M-x call with optional arg; call from Elisp
From: |
Emanuel Berg |
Subject: |
Re: M-x call with optional arg; call from Elisp |
Date: |
Tue, 28 May 2013 21:52:04 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/23.4 (gnu/linux) |
Stefan Monnier <monnier@iro.umontreal.ca> writes:
>> 1. How can I call a function with M-x and provide an optional
>> string arg?
>
> You have to put in the `interactive' spec a description of what
> value to pass.
Yes, that did it: this works from M-x:
(defun words (&optional opts)
"Count buffer words with wc OPTS, or wc -w if not OPTS is given."
(interactive "s (RET for -w) options to wc: ")
(let*((options (if (not (string= "" opts)) opts "-w"))
(count-cmd (format "wc %s" options)) )
(if mark-active
(shell-command-on-region (region-beginning) (region-end) count-cmd)
(shell-command-on-region (point-min) (point-max) count-cmd) )))
> defvar does not define the variable, nor declares it as local.
> Quite the opposite, it basically declares it as global (or rather
> as dynamically-scoped, which ends up being fairly close). You want
> to use let.
Aha, when I started with Elisp, I always used let, but then I found
defvar and started using it, because the syntax is much easier to
use. I thought defvar gave a local variable if in a defun.
> Don't use shell-command-on-region from Elisp. Use
> call-process-region instead.
The above function seems to work. shell-command-on-region and
call-process-region are not syntactically interchangeable, but I'll
do it if you care to tell me the advantage.
--
Emanuel Berg - programmer (hire me! CV below)
computer projects: http://user.it.uu.se/~embe8573
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