Emacs insert empty string

Emacs insert empty string

[Kenneth Brun Nielsen]

Hi,

I'm a happy user of Emacs 23.2.1.

One thing annoys me, though.

The string rectangle insert function (CTRL-x rt) is neat. But
sometimes you need to insert an empty string. I cannot do this,
because if I type an empty string (i.e. press Enter), then it insert
the "default" string, which is equal to the last inserted string.

How can I insert an empty string?

Best regards,
Kenneth

Re: Emacs insert empty string

[PJ Weisberg]

On Wed, Mar 23, 2011 at 6:46 PM, Kenneth Brun Nielsen
<kenneth.brun.nielsen@gmail.com> wrote:
> Hi,
>
> I'm a happy user of Emacs 23.2.1.
>
> One thing annoys me, though.
>
> The string rectangle insert function (CTRL-x rt) is neat. But
> sometimes you need to insert an empty string. I cannot do this,
> because if I type an empty string (i.e. press Enter), then it insert
> the "default" string, which is equal to the last inserted string.
>
> How can I insert an empty string?

(CTRL-x rd)

Re: Emacs insert empty string

[Peter Dyballa]

Am 24.03.2011 um 02:46 schrieb Kenneth Brun Nielsen:

> How can I insert an empty string?


What is "an empty string?" Can you exactly and comprehensively  
describe this? Is it defined in Wikipedia? And give us a few examples?

--
Greetings

   Pete

There is no national science just as there is no national  
multiplication table; what is national is no longer science.
				– Anton Checov

Re: Emacs insert empty string

[Kenneth Brun Nielsen]

On Mar 24, 5:47 am, PJ Weisberg <p...@irregularexpressions.net> wrote:
> On Wed, Mar 23, 2011 at 6:46 PM, Kenneth Brun Nielsen
>
> <kenneth.brun.niel...@gmail.com> wrote:
> > Hi,
>
> > I'm a happy user of Emacs 23.2.1.
>
> > One thing annoys me, though.
>
> > The string rectangle insert function (CTRL-x rt) is neat. But
> > sometimes you need to insert an empty string. I cannot do this,
> > because if I type an empty string (i.e. press Enter), then it insert
> > the "default" string, which is equal to the last inserted string.
>
> > How can I insert an empty string?
>
> (CTRL-x rd)

It doesn't seem to work in this context.

/Kenneth

Re: Emacs insert empty string

[Kenneth Brun Nielsen]

On Mar 24, 10:49 am, Peter Dyballa <Peter_Dyba...@Web.DE> wrote:
> Am 24.03.2011 um 02:46 schrieb Kenneth Brun Nielsen:
>
> > How can I insert an empty string?
>
> What is "an empty string?" Can you exactly and comprehensively  
> describe this? Is it defined in Wikipedia? And give us a few examples?

An empty string is the thing between the quotes here: "". My geek
level is not high enough to rephrase it further :)

An example is this command file consisting of 100001 commands:

---
command 1
command 2
..
command 100000
command 100001
---
Now I want to outcomment the first 1000 commands. I select the 1000
lines and use 'CTRL-x rt' for rectangle mode, and insert a "*" in
front of the first 1000 lines. Now my file looks like this:
---
*command 1
*command 2
..
*command 1000
command 1001
..
command 100000
command 100001
---
Now I "regret" outcommenting the commands 600-800. Again I select the
lines/columns of interest and use the 'CTRL-x rt' command and remove
the "*" column (i.e. replace the first column with an empty string)
for that specific lines, targetting a file like this:
---
*command 1
..
*command 599
command 600
..
command 800
*command 801
..
*command 1000
command 1001
..
command 100000
command 100001
---

However this last step doesn't work as intended. Because I can not
replace with an empty string. Simply pressing "Enter" will choose the
default string, which is the equivalent to the previously inserted
string "*".

Does my explanation make sense?

/Kenneth

Re: Emacs insert empty string

[Deniz Dogan]

2011/3/24 Peter Dyballa <Peter_Dyballa@web.de>:
>
> Am 24.03.2011 um 02:46 schrieb Kenneth Brun Nielsen:
>
>> How can I insert an empty string?
>
>
> What is "an empty string?" Can you exactly and comprehensively describe
> this? Is it defined in Wikipedia? And give us a few examples?
>

http://en.wikipedia.org/wiki/Empty_string

Cited:

"In computer science and formal language theory, the empty string (or
null string)[1] is the unique string of length zero. It is denoted
with λ or sometimes Λ or ε.

The empty string is distinct from a null reference in that in an
object-oriented programming language a null reference to a string type
doesn't point to a string object and will cause an error were one to
try to perform any operation on it. The empty string is still a string
upon which string operations may be attempted.

A related concept is the empty language ∅, a formal language that
contains no strings."

-- 
Deniz Dogan

Re: Emacs insert empty string

[Deniz Dogan]

2011/3/24 Kenneth Brun Nielsen <kenneth.brun.nielsen@gmail.com>:
> On Mar 24, 5:47 am, PJ Weisberg <p...@irregularexpressions.net> wrote:
>> On Wed, Mar 23, 2011 at 6:46 PM, Kenneth Brun Nielsen
>>
>> <kenneth.brun.niel...@gmail.com> wrote:
>> > Hi,
>>
>> > I'm a happy user of Emacs 23.2.1.
>>
>> > One thing annoys me, though.
>>
>> > The string rectangle insert function (CTRL-x rt) is neat. But
>> > sometimes you need to insert an empty string. I cannot do this,
>> > because if I type an empty string (i.e. press Enter), then it insert
>> > the "default" string, which is equal to the last inserted string.
>>
>> > How can I insert an empty string?
>>
>> (CTRL-x rd)
>
> It doesn't seem to work in this context.
>

What is it that doesn't work? Give us a way to reproduce the problem.

-- 
Deniz Dogan

Re: Emacs insert empty string

[Deniz Dogan]

2011/3/24 Kenneth Brun Nielsen <kenneth.brun.nielsen@gmail.com>:
> On Mar 24, 10:49 am, Peter Dyballa <Peter_Dyba...@Web.DE> wrote:
>> Am 24.03.2011 um 02:46 schrieb Kenneth Brun Nielsen:
>>
>> > How can I insert an empty string?
>>
>> What is "an empty string?" Can you exactly and comprehensively
>> describe this? Is it defined in Wikipedia? And give us a few examples?
>
> An empty string is the thing between the quotes here: "". My geek
> level is not high enough to rephrase it further :)
>
> An example is this command file consisting of 100001 commands:
>
> ---
> command 1
> command 2
> ..
> command 100000
> command 100001
> ---
> Now I want to outcomment the first 1000 commands. I select the 1000
> lines and use 'CTRL-x rt' for rectangle mode, and insert a "*" in
> front of the first 1000 lines. Now my file looks like this:
> ---
> *command 1
> *command 2
> ..
> *command 1000
> command 1001
> ..
> command 100000
> command 100001
> ---
> Now I "regret" outcommenting the commands 600-800. Again I select the
> lines/columns of interest and use the 'CTRL-x rt' command and remove
> the "*" column (i.e. replace the first column with an empty string)
> for that specific lines, targetting a file like this:
> ---
> *command 1
> ..
> *command 599
> command 600
> ..
> command 800
> *command 801
> ..
> *command 1000
> command 1001
> ..
> command 100000
> command 100001
> ---
>
> However this last step doesn't work as intended. Because I can not
> replace with an empty string. Simply pressing "Enter" will choose the
> default string, which is the equivalent to the previously inserted
> string "*".
>

This is where you should use C-x r d instead. It will delete the
rectangle you have selected and is the equivalent of replacing its
contents with the empty string.

-- 
Deniz Dogan

Re: Emacs insert empty string

[Kenneth Brun Nielsen]

On Mar 24, 5:47 am, PJ Weisberg <p...@irregularexpressions.net> wrote:
> On Wed, Mar 23, 2011 at 6:46 PM, Kenneth Brun Nielsen
>
> <kenneth.brun.niel...@gmail.com> wrote:
> > Hi,
>
> > I'm a happy user of Emacs 23.2.1.
>
> > One thing annoys me, though.
>
> > The string rectangle insert function (CTRL-x rt) is neat. But
> > sometimes you need to insert an empty string. I cannot do this,
> > because if I type an empty string (i.e. press Enter), then it insert
> > the "default" string, which is equal to the last inserted string.
>
> > How can I insert an empty string?
>
> (CTRL-x rd)

Aha. Now I understand. So I use (CTRL-x rd) INSTEAD OF (CTRL-x rt).
Initially I thought, that I should press (CTRL-x rd) in the string
dialog of the (CTRL-x rt) command.

Thanks!

Best regards,
Kenneth

Re: Emacs insert empty string

[Kenneth Brun Nielsen]

On Mar 24, 11:42 am, Deniz Dogan <deniz.a.m.do...@gmail.com> wrote:
> 2011/3/24 Kenneth Brun Nielsen <kenneth.brun.niel...@gmail.com>:
>
>
>
> > On Mar 24, 5:47 am, PJ Weisberg <p...@irregularexpressions.net> wrote:
> >> On Wed, Mar 23, 2011 at 6:46 PM, Kenneth Brun Nielsen
>
> >> <kenneth.brun.niel...@gmail.com> wrote:
> >> > Hi,
>
> >> > I'm a happy user of Emacs 23.2.1.
>
> >> > One thing annoys me, though.
>
> >> > The string rectangle insert function (CTRL-x rt) is neat. But
> >> > sometimes you need to insert an empty string. I cannot do this,
> >> > because if I type an empty string (i.e. press Enter), then it insert
> >> > the "default" string, which is equal to the last inserted string.
>
> >> > How can I insert an empty string?
>
> >> (CTRL-x rd)
>
> > It doesn't seem to work in this context.
>
> What is it that doesn't work?

I misunderstood the suggestion. It works, if used in the right manner
(please refer to my previous post).

Best regards,
Kenneth

Re: Emacs insert empty string

[Kenneth Brun Nielsen]

On Mar 24, 11:50 am, Deniz Dogan <deniz.a.m.do...@gmail.com> wrote:
> 2011/3/24 Kenneth Brun Nielsen <kenneth.brun.niel...@gmail.com>:

> > However this last step doesn't work as intended. Because I can not
> > replace with an empty string. Simply pressing "Enter" will choose the
> > default string, which is the equivalent to the previously inserted
> > string "*".
>
> This is where you should use C-x r d instead. It will delete the
> rectangle you have selected and is the equivalent of replacing its
> contents with the empty string.
>
> --
> Deniz Dogan

It seems, there is some delay in this Group, so I didn't see this post
before posting the previous ones.

Anyway, you are absolutely right - it's all clear to me now :)

Best regards,
Kenneth

Re: Emacs insert empty string

[Peter Dyballa]

Am 24.03.2011 um 11:25 schrieb Kenneth Brun Nielsen:

> An empty string is the thing between the quotes here: "".

And it doesn't work to mark a region and then perform

	C-x r t " " RET		; the SPACE between " and " only for transcription!

? That's strange, really! For me it works.

--
Greetings

   Pete

A blizzard is when it snows sideways.

Re: Emacs insert empty string

[Kenneth Brun Nielsen]

On Mar 24, 12:09 pm, Peter Dyballa <Peter_Dyba...@Web.DE> wrote:
> Am 24.03.2011 um 11:25 schrieb Kenneth Brun Nielsen:
>
> > An empty string is the thing between the quotes here: "".
>
> And it doesn't work to mark a region and then perform
>
>         C-x r t " " RET               ; the SPACE between " and " only for transcription!
>
> ? That's strange, really! For me it works.

It worked in my old RHEL4 installed Emacs - I guess that's why I never
missed (CTRL-x rc). In this new verision of Emacs, it insist on
inserting the default string (which is not empty, if you have used the
command previously i the same session).

Best regards,
Kenneth

Re: Emacs insert empty string

[David Kastrup]

Peter Dyballa <Peter_Dyballa@Web.DE> writes:

> Am 24.03.2011 um 11:25 schrieb Kenneth Brun Nielsen:
>
>> An empty string is the thing between the quotes here: "".
>
> And it doesn't work to mark a region and then perform
>
> 	C-x r t " " RET ; the SPACE between " and " only for
> transcription!
>
> ? That's strange, really! For me it works.

The thing between the quotes, not including them.

-- 
David Kastrup

Re: Emacs insert empty string

[Peter Dyballa]

Am 24.03.2011 um 11:25 schrieb Kenneth Brun Nielsen:

> Now I "regret" outcommenting the commands 600-800. Again I select the
> lines/columns of interest and use the 'CTRL-x rt' command and remove
> the "*" column (i.e. replace the first column with an empty string)


The documentation, in my interpretation and understanding, does not  
tell it would work. Because the rectangle functions *insert* and don't  
*overwrite* (maybe they would do when you activate overwrite-mode).  
And an empty inserted stays invisible otherwise it would not be an  
empty string but a (file and disk space) consuming string. Since  
decades (or such) I do something like this these modern days on the  
marked first column (i.e., mark in left-most column, point one column  
forward to the right, or vice-versa, or in numbers: 0 and 1):

	C-x r k

> Does my explanation make sense?

Yes.

--
Greetings

   Pete

To most people solutions mean finding the answers. But to chemists  
solutions
are things that are still all mixed up.

Re: Emacs insert empty string

[David Kastrup]

Peter Dyballa <Peter_Dyballa@Web.DE> writes:

> Am 24.03.2011 um 11:25 schrieb Kenneth Brun Nielsen:
>
>> Now I "regret" outcommenting the commands 600-800. Again I select the
>> lines/columns of interest and use the 'CTRL-x rt' command and remove
>> the "*" column (i.e. replace the first column with an empty string)
>
>
> The documentation, in my interpretation and understanding, does not
> tell it would work. Because the rectangle functions *insert* and don't
> *overwrite* (maybe they would do when you activate
> overwrite-mode).

Huh?

    C-x r t runs the command string-rectangle, which is an interactive
    autoloaded Lisp function in `rect.el'.

    It is bound to C-x r t.

    (string-rectangle START END STRING)

    Replace rectangle contents with STRING on each line.
    The length of STRING need not be the same as the rectangle width.

    Called from a program, takes three args; START, END and STRING.

What about "replace rectangle contents" do you not understand?

-- 
David Kastrup

Re: Emacs insert empty string

[Le Wang]

On Thu, Mar 24, 2011 at 6:56 PM, Kenneth Brun Nielsen
<kenneth.brun.nielsen@gmail.com> wrote:
> On Mar 24, 11:42 am, Deniz Dogan <deniz.a.m.do...@gmail.com> wrote:
>> 2011/3/24 Kenneth Brun Nielsen <kenneth.brun.niel...@gmail.com>:
>>
>>
>>
>> > On Mar 24, 5:47 am, PJ Weisberg <p...@irregularexpressions.net> wrote:
>> >> On Wed, Mar 23, 2011 at 6:46 PM, Kenneth Brun Nielsen
>>
>> >> <kenneth.brun.niel...@gmail.com> wrote:
>> >> > Hi,
>>
>> >> > I'm a happy user of Emacs 23.2.1.
>>
>> >> > One thing annoys me, though.
>>
>> >> > The string rectangle insert function (CTRL-x rt) is neat. But
>> >> > sometimes you need to insert an empty string. I cannot do this,
>> >> > because if I type an empty string (i.e. press Enter), then it insert
>> >> > the "default" string, which is equal to the last inserted string.
>>
>> >> > How can I insert an empty string?
>>
>> >> (CTRL-x rd)
>>
>> > It doesn't seem to work in this context.
>>
>> What is it that doesn't work?
>
> I misunderstood the suggestion. It works, if used in the right manner
> (please refer to my previous post).

Yeah, you asked your original question in a really weird way.  I'm
really surprised PJ got it in one shot!  Good for him.

-- 
Le

Re: Emacs insert empty string

[Tassilo Horn]

Kenneth Brun Nielsen <kenneth.brun.nielsen@gmail.com> writes:

Hi Kenneth,

> Now I want to outcomment the first 1000 commands.
> [...]
> Now I "regret" outcommenting the commands 600-800.

If commenting out/in is your desire, why not simply use M-;
(comment-dwim)?  That will even ask you for the comment syntax (* in
your case), if it is not defined by the language mode (if any).

Bye,
Tassilo

Re: Emacs insert empty string

[Kenneth Brun Nielsen]

On Mar 24, 12:53 pm, Tassilo Horn <tass...@member.fsf.org> wrote:

> If commenting out/in is your desire..

I have other desires that involves removing columns. The commenting
thing was just an example. But thanks for your suggestion.

/Kenneth

Re: Emacs insert empty string

[Peter Dyballa]

Am 24.03.2011 um 12:24 schrieb David Kastrup:

> What about "replace rectangle contents" do you not understand?


That it's now replace and not insert. I am bloody old school...

--
Mit friedvollen Grüßen

   Pete

Sending unsolicited commercial eMail to this account incurs a fee of €  
500 per message and acknowledges the legality of this contract.

Re: Emacs insert empty string

[David Kastrup]

Peter Dyballa <Peter_Dyballa@Web.DE> writes:

> Am 24.03.2011 um 12:24 schrieb David Kastrup:
>
>> What about "replace rectangle contents" do you not understand?
>
>
> That it's now replace and not insert. I am bloody old school...

commit 734a9f369ae0c5f4e4f28610bb4be3c96b74e2a2
Author:	Gerd Moellmann <gerd@gnu.org>  Tue Apr 24 12:56:26 2001
Committer:	Gerd Moellmann <gerd@gnu.org>  Tue Apr 24 12:56:26 2001

(string-rectangle): Revert to 20.x behaviour.
(replace-rectangle): Make it an alias for string-rectangle.
(string-insert-rectangle): New function.


If you were bloody old school, you'd rejoice in having back the 20.x
behavior.  Instead you complain about a change that is not even 10 years
old.

-- 
David Kastrup

Re: Emacs insert empty string

[Peter Dyballa]

Am 24.03.2011 um 14:44 schrieb David Kastrup:

> Instead you complain about a change that is not even 10 years old.


Oh! I did not think I would complain – I thought it was a weak excuse  
of not reading the manuals...

--
Mit friedvollen Grüßen

   Pete

Diese Nachricht wurde mit einer Taschenlampe ins offene Ende eines  
Glasfaserkabels gemorst.

Re: Emacs insert empty string

[Ilya Zakharevich]

On 2011-03-24, Kenneth Brun Nielsen <kenneth.brun.nielsen@gmail.com> wrote:
> Now I "regret" outcommenting the commands 600-800. Again I select the
> lines/columns of interest and use the 'CTRL-x rt' command and remove
> the "*" column (i.e. replace the first column with an empty string)
> for that specific lines, targetting a file like this:
  ...
> However this last step doesn't work as intended. Because I can not
> replace with an empty string. Simply pressing "Enter" will choose the
> default string, which is the equivalent to the previously inserted
> string "*".

Works without any quirk here (v21.4).  With newer versions, would not
pressing

  a BACKSPACE

"ignore" the default value?

Ilya