Inserting at particular buffer position

Inserting at particular buffer position

[Heime]

The function "insert", inserts characters into the current buffer, at point, moving point forward.
But how can I insert at a particular position (row column).

Re: Inserting at particular buffer position

[Eli Zaretskii]

> Date: Sun, 04 Dec 2022 01:12:52 +0000
> From: Heime <heimeborgia@protonmail.com>
> 
> 
> The function "insert", inserts characters into the current buffer, at point, moving point forward.
> But how can I insert at a particular position (row column).

You need to move point there first.  For example, with goto-char (if you
know the buffer position), or with forward-line followed by move-to-column
(of you know the line and column).

Re: Inserting at particular buffer position

[Heime]

------- Original Message -------
On Sunday, December 4th, 2022 at 7:24 AM, Eli Zaretskii <eliz@gnu.org> wrote:


> > Date: Sun, 04 Dec 2022 01:12:52 +0000
> > From: Heime heimeborgia@protonmail.com
> > 
> > The function "insert", inserts characters into the current buffer, at point, moving point forward.
> > But how can I insert at a particular position (row column).
> 
> 
> You need to move point there first. For example, with goto-char (if you
> know the buffer position), or with forward-line followed by move-to-column
> (of you know the line and column).

A problem that I encounter is that if the position (row col) is not available,
point does not switch to the correct position.

Re: Inserting at particular buffer position

[Eli Zaretskii]

> Date: Sun, 04 Dec 2022 08:04:03 +0000
> From: Heime <heimeborgia@protonmail.com>
> Cc: help-gnu-emacs@gnu.org
> 
> ------- Original Message -------
> On Sunday, December 4th, 2022 at 7:24 AM, Eli Zaretskii <eliz@gnu.org> wrote:
> 
> 
> > > Date: Sun, 04 Dec 2022 01:12:52 +0000
> > > From: Heime heimeborgia@protonmail.com
> > > 
> > > The function "insert", inserts characters into the current buffer, at point, moving point forward.
> > > But how can I insert at a particular position (row column).
> > 
> > 
> > You need to move point there first. For example, with goto-char (if you
> > know the buffer position), or with forward-line followed by move-to-column
> > (of you know the line and column).
> 
> A problem that I encounter is that if the position (row col) is not available,
> point does not switch to the correct position.

What do you mean by "position not available"?

How do you compute that position's row and column, if it isn't available?

Re: Inserting at particular buffer position

[Heime]

------- Original Message -------
On Sunday, December 4th, 2022 at 10:01 AM, Eli Zaretskii <eliz@gnu.org> wrote:


> > Date: Sun, 04 Dec 2022 08:04:03 +0000
> > From: Heime heimeborgia@protonmail.com
> > Cc: help-gnu-emacs@gnu.org
> > 
> > ------- Original Message -------
> > On Sunday, December 4th, 2022 at 7:24 AM, Eli Zaretskii eliz@gnu.org wrote:
> > 
> > > > Date: Sun, 04 Dec 2022 01:12:52 +0000
> > > > From: Heime heimeborgia@protonmail.com
> > > > 
> > > > The function "insert", inserts characters into the current buffer, at point, moving point forward.
> > > > But how can I insert at a particular position (row column).
> > > 
> > > You need to move point there first. For example, with goto-char (if you
> > > know the buffer position), or with forward-line followed by move-to-column
> > > (of you know the line and column).
> > 
> > A problem that I encounter is that if the position (row col) is not available,
> > point does not switch to the correct position.
> 
> 
> What do you mean by "position not available"?
> 
> How do you compute that position's row and column, if it isn't available?

Suppose I insert in the current buffer, to a line larger than the greatest line
where the cursor can go.  Nothing gets printed after that.  And if I try to print
to a column which is larger than available whitespace, things do not get printed.

Re: Inserting at particular buffer position

[Eli Zaretskii]

> Date: Sun, 04 Dec 2022 11:16:47 +0000
> From: Heime <heimeborgia@protonmail.com>
> Cc: help-gnu-emacs@gnu.org
> 
> > > A problem that I encounter is that if the position (row col) is not available,
> > > point does not switch to the correct position.
> > 
> > 
> > What do you mean by "position not available"?
> > 
> > How do you compute that position's row and column, if it isn't available?
> 
> Suppose I insert in the current buffer, to a line larger than the greatest line
> where the cursor can go.  Nothing gets printed after that.  And if I try to print
> to a column which is larger than available whitespace, things do not get printed.

Insert enough newlines where you lack lines, and insert enough SPC
characters to have the column you want.

Re: Inserting at particular buffer position

[Eli Zaretskii]

> Date: Sun, 04 Dec 2022 13:49:39 +0200
> From: Eli Zaretskii <eliz@gnu.org>
> 
> > Date: Sun, 04 Dec 2022 11:16:47 +0000
> > From: Heime <heimeborgia@protonmail.com>
> > Cc: help-gnu-emacs@gnu.org
> > 
> > > > A problem that I encounter is that if the position (row col) is not available,
> > > > point does not switch to the correct position.
> > > 
> > > 
> > > What do you mean by "position not available"?
> > > 
> > > How do you compute that position's row and column, if it isn't available?
> > 
> > Suppose I insert in the current buffer, to a line larger than the greatest line
> > where the cursor can go.  Nothing gets printed after that.  And if I try to print
> > to a column which is larger than available whitespace, things do not get printed.
> 
> Insert enough newlines where you lack lines, and insert enough SPC
> characters to have the column you want.

Also, the function move-to-column can optionally insert SPC characters if
the line is shorter than the column to which you want to get.

Re: Inserting at particular buffer position

[Heime]

------- Original Message -------
On Sunday, December 4th, 2022 at 11:49 AM, Eli Zaretskii <eliz@gnu.org> wrote:


> > Date: Sun, 04 Dec 2022 11:16:47 +0000
> > From: Heime heimeborgia@protonmail.com
> > Cc: help-gnu-emacs@gnu.org
> > 
> > > > A problem that I encounter is that if the position (row col) is not available,
> > > > point does not switch to the correct position.
> > > 
> > > What do you mean by "position not available"?
> > > 
> > > How do you compute that position's row and column, if it isn't available?
> > 
> > Suppose I insert in the current buffer, to a line larger than the greatest line
> > where the cursor can go. Nothing gets printed after that. And if I try to print
> > to a column which is larger than available whitespace, things do not get printed.
> 
> 
> Insert enough newlines where you lack lines, and insert enough SPC
> characters to have the column you want.

I want to make a buffer with the respective text inserted automatically, without
any inputs from the user.

Re: Inserting at particular buffer position

[Eli Zaretskii]

> Date: Sun, 04 Dec 2022 12:27:05 +0000
> From: Heime <heimeborgia@protonmail.com>
> Cc: help-gnu-emacs@gnu.org
> 
> ------- Original Message -------
> On Sunday, December 4th, 2022 at 11:49 AM, Eli Zaretskii <eliz@gnu.org> wrote:
> 
> 
> > > Date: Sun, 04 Dec 2022 11:16:47 +0000
> > > From: Heime heimeborgia@protonmail.com
> > > Cc: help-gnu-emacs@gnu.org
> > > 
> > > > > A problem that I encounter is that if the position (row col) is not available,
> > > > > point does not switch to the correct position.
> > > > 
> > > > What do you mean by "position not available"?
> > > > 
> > > > How do you compute that position's row and column, if it isn't available?
> > > 
> > > Suppose I insert in the current buffer, to a line larger than the greatest line
> > > where the cursor can go. Nothing gets printed after that. And if I try to print
> > > to a column which is larger than available whitespace, things do not get printed.
> > 
> > 
> > Insert enough newlines where you lack lines, and insert enough SPC
> > characters to have the column you want.
> 
> I want to make a buffer with the respective text inserted automatically, without
> any inputs from the user.

I meant your Lisp program should make these insertions, not the user.

Re: Inserting at particular buffer position

[Jean Louis]

* Heime <heimeborgia@protonmail.com> [2022-12-04 04:14]:
> The function "insert", inserts characters into the current buffer,
> at point, moving point forward.  But how can I insert at a
> particular position (row column).

I have Deja Vu.

(defun goto-x-y (x y)
  "Goto to line X, char Y."
  (goto-line x)
  (goto-char (point-at-bol))
  (forward-char y))


-- 
Jean

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Re: Inserting at particular buffer position

[Jean Louis]

* Heime <heimeborgia@protonmail.com> [2022-12-04 11:06]:
> A problem that I encounter is that if the position (row col) is not
> available, point does not switch to the correct position.

Good point, so make sure you have enough empty spaces.

-- 
Jean

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https://www.fsf.org/campaigns

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Re: Inserting at particular buffer position

[Jean Louis]

* Heime <heimeborgia@protonmail.com> [2022-12-04 11:06]:
> A problem that I encounter is that if the position (row col) is not
> available, point does not switch to the correct position.

Fill it with spaces.

-- 
Jean

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https://www.fsf.org/campaigns

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https://stallmansupport.org/

Re: Inserting at particular buffer position

[Heime]

------- Original Message -------
On Sunday, December 4th, 2022 at 1:22 PM, Jean Louis <bugs@gnu.support> wrote:


> * Heime heimeborgia@protonmail.com [2022-12-04 11:06]:
> 
> > A problem that I encounter is that if the position (row col) is not
> > available, point does not switch to the correct position.
> 
> 
> Good point, so make sure you have enough empty spaces.
> 
> --
> Jean

What can one do to get a new line and go to the beginning of the new line?

Re: Inserting at particular buffer position

[Jean Louis]

* Heime <heimeborgia@protonmail.com> [2022-12-04 16:53]:
> What can one do to get a new line and go to the beginning of the new line?

By advise of Eli, using `move-to-column' that insert spaces if
necessary:

(defun goto-x-y-unconditionally (x y)
  "Goto to line X, char Y unconditionally."
  (let ((lines (count-lines (point-min) (point-max))))
    (when (< lines x)
      (goto-char (point-max))
      (insert "\n" (make-string (- x lines) ?\n)))
    (goto-line x)
    (goto-char (point-at-bol))
    (move-to-column y t)))


-- 
Jean

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https://www.fsf.org/campaigns

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Re: Inserting at particular buffer position

[Dr Rainer Woitok]

On Sunday, 2022-12-04 16:21:41 +0300, Jean Louis wrote:

> * Heime <heimeborgia@protonmail.com> [2022-12-04 04:14]:
> > The function "insert", inserts characters into the current buffer,
> > at point, moving point forward.  But how can I insert at a
> > particular position (row column).
> 
> I have Deja Vu.
> 
> (defun goto-x-y (x y)
>   "Goto to line X, char Y."
>   (goto-line x)
>   (goto-char (point-at-bol))
>   (forward-char y))

Heime,

a week or so ago  you flabbergasted me  (and probably others)  with your
claim that programming  is neither engineering  nor science,  but rather
sports.   This claim made me gasp at first,  but gradually  I am getting
your point.  While what makes up the Art of Programming can be looked-up
in Donald Knuth's book,  what makes up the  Sports of Programming can be
looked-up in your mails: just stubbornly nag  people with sometimes very
imprecise questions,  assumptions  and allegations,  and sooner or later
good-natured people like Jean Louis and plenty of others  fall victim to
your tactics and start writing you the programmes you need.

You have meanwhile got so many code snippets to solve your problems that
with a little additional manual reading, thinking,  testing and adapting
your programme(s) should almost be working.

I take this as a Proof of Concept that programming is sports.  Congratu-
lations :-)

Sincerely,
  Rainer

Re: Inserting at particular buffer position

[Heime]

Sent with Proton Mail secure email.

------- Original Message -------
On Sunday, December 4th, 2022 at 3:52 PM, Dr Rainer Woitok <rainer.woitok@gmail.com> wrote:


> On Sunday, 2022-12-04 16:21:41 +0300, Jean Louis wrote:
> 
> > * Heime heimeborgia@protonmail.com [2022-12-04 04:14]:
> > 
> > > The function "insert", inserts characters into the current buffer,
> > > at point, moving point forward. But how can I insert at a
> > > particular position (row column).
> > 
> > I have Deja Vu.
> > 
> > (defun goto-x-y (x y)
> > "Goto to line X, char Y."
> > (goto-line x)
> > (goto-char (point-at-bol))
> > (forward-char y))
> 
> 
> Heime,
> 
> a week or so ago you flabbergasted me (and probably others) with your
> claim that programming is neither engineering nor science, but rather
> sports. This claim made me gasp at first, but gradually I am getting
> your point. While what makes up the Art of Programming can be looked-up
> in Donald Knuth's book, what makes up the Sports of Programming can be
> looked-up in your mails: just stubbornly nag people with sometimes very
> imprecise questions, assumptions and allegations, and sooner or later
> good-natured people like Jean Louis and plenty of others fall victim to
> your tactics and start writing you the programmes you need.

Sounds like an episode from "Our Gang", Doctor.

> You have meanwhile got so many code snippets to solve your problems that
> with a little additional manual reading, thinking, testing and adapting
> your programme(s) should almost be working.
> 
> I take this as a Proof of Concept that programming is sports. Congratu-
> lations :-)

I'll invite you to the party for sure.
 
> Sincerely,
> Rainer

Re: Inserting at particular buffer position

[Heime]

------- Original Message -------
On Sunday, December 4th, 2022 at 1:30 PM, Jean Louis <bugs@gnu.support> wrote:


> * Heime heimeborgia@protonmail.com [2022-12-04 11:06]:
> 
> > A problem that I encounter is that if the position (row col) is not
> > available, point does not switch to the correct position.
> 
> 
> Fill it with spaces.
> 
> --
> Jean

I want to track the buffer position of five things.  Could store them in an list.
How could I set the list up?

Re: Inserting at particular buffer position

[Jean Louis]

* Heime <heimeborgia@protonmail.com> [2022-12-05 09:22]:
> I want to track the buffer position of five things.  Could store
> them in an list.  How could I set the list up?

Do you mean five buffer positions like five chars in a buffer?

-- 
Jean

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