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Re: How to detect C-u supplied arguments from other prefix arguments
From: |
Dieter Wilhelm |
Subject: |
Re: How to detect C-u supplied arguments from other prefix arguments |
Date: |
Thu, 09 Aug 2007 08:52:58 +0200 |
User-agent: |
Gnus/5.11 (Gnus v5.11) Emacs/22.1 (gnu/linux) |
Barry Margolin <barmar@alum.mit.edu> writes:
> In article <1186576048.530383.47680@q75g2000hsh.googlegroups.com>,
> dieter.wilhelm@googlemail.com wrote:
>
>> On 8 ao?t, 13:55, bojohan+n...@dd.chalmers.se (Johan Bockg?rd) wrote:
>> > Dieter Wilhelm <die...@duenenhof-wilhelm.de> writes:
>> > > I'd like to detect whether prefix arguments of a command are supplied
>> > > by C-u or otherwise.
>> >
>> > > My idea is to use this-command-keys and compare it to some string,
>> > > like the following pseudo code:
>> >
>> > > (defun bla (arg)
>> > > (interactive "p")
>> > > (when (string= "C-u" (substring (this-command-keys) 0 2))
>> > > (message "hurray")))
>> >
>> > > I just don't understand how to compare key sequences.
>> >
>> > You want to check for the character ^U, not the three-character string
>> > `C - u'. Like
>> >
>> > (eq ?\C-u (aref (this-command-keys) 0))
>>
>> hurray it works, thanks a lot!
>> >
>> > (The whole idea seems a bit ugly though.)
>>
>> Why? In Emacs there are just too little short key combinations free.
>> I'd like to achieve
>> a switch for certain functions depending whether their arguments ARG
>> are supplied by C-u or not.
>>
>> For example: M-d might kill ARG word with the following boundary/
>> whitespace or without,
>> or C-t might drag a character ARG chars away and in the other case
>> merely transpose neighbouring chars some ARG chars away.
>
> And what if the user decides to bind a different keystroke to
> universal-argument?
True, from this point of view it's a very bad idea, C-u would be not
customisable any longer. But I think it's only a marginal problem and
on the other hand I feel the need to expand the Emacs key-binding
space, this is my only idea so far and I will test its feasibility.
Thanks
--
Best wishes
H. Dieter Wilhelm
Darmstadt, Germany
Re: How to detect C-u supplied arguments from other prefix arguments, Stefan Monnier, 2007/08/09