"Point" vs. "cursor" in documentation

"Point" vs. "cursor" in documentation

[Siraphob (Ben) Phipathananunth]

I've noticed usage of "the cursor" and "point" throughout manuals and 
doc-strings.  In what context is one preferred over the other?

--
Siraphob (Ben) Phipathananunth

RE: "Point" vs. "cursor" in documentation

[Drew Adams]

> I've noticed usage of "the cursor" and "point" throughout manuals and
> doc-strings.  In what context is one preferred over the other?

Point is the buffer position of the cursor (aka text cursor).

In the Emacs manual (`C-h r'), `i point' and `i cursor'
both take you to node `Point', which explains this.

Re: "Point" vs. "cursor" in documentation

[Jean-Christophe Helary]

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> On Jul 3, 2018, at 23:27, Drew Adams <drew.adams@oracle.com> wrote:
> 
>> I've noticed usage of "the cursor" and "point" throughout manuals and
>> doc-strings.  In what context is one preferred over the other?
> 
> Point is the buffer position of the cursor (aka text cursor).

From the Introduction to Emacs Lisp:

"In Emacs, the current position of the cursor is called point. The expression (point) returns a number that tells you where the cursor is located as a count of the number of characters from the beginning of the buffer up to point."


Jean-Christophe Helary
-----------------------------------------------
http://mac4translators.blogspot.com @brandelune



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Re: "Point" vs. "cursor" in documentation

[John Yates]

On Tue, Jul 3, 2018 at 10:38 AM Jean-Christophe Helary
<brandelune@gmail.com> wrote:
> From the Introduction to Emacs Lisp:
>
> "In Emacs, the current position of the cursor is called point. The expression (point) returns a number that tells you where the cursor is located as a count of the number of characters from the beginning of the buffer up to point."

Historical note:  Emacs did not invent this terminology.  When I used
TECO commands were explained / defined in terms of "point".  For all I
know TECO may in turn have inherited that terminology from even
earlier editors (c.f. MIT's ITS or its PDP-1).

/john

Re: "Point" vs. "cursor" in documentation

[Richard Stallman]

[[[ To any NSA and FBI agents reading my email: please consider    ]]]
[[[ whether defending the US Constitution against all enemies,     ]]]
[[[ foreign or domestic, requires you to follow Snowden's example. ]]]

  > Historical note:  Emacs did not invent this terminology.  When I used
  > TECO commands were explained / defined in terms of "point".  For all I
  > know TECO may in turn have inherited that terminology from even
  > earlier editors (c.f. MIT's ITS or its PDP-1).

ITS, the Incompatible Timesharing System, was not a text editor.
Its text editor was TECO -- the very same TECO on top of which
EMACS was implemented.

-- 
Dr Richard Stallman
President, Free Software Foundation (https://gnu.org, https://fsf.org)
Internet Hall-of-Famer (https://internethalloffame.org)

Re: "Point" vs. "cursor" in documentation

[John Yates]

On Tue, Jul 3, 2018 at 7:04 PM Richard Stallman <rms@gnu.org> wrote:
> ITS, the Incompatible Timesharing System, was not a text editor.
> Its text editor was TECO -- the very same TECO on top of which
> EMACS was implemented.

Yes, I am aware that ITS was an OS, not an editor.  Similarly the
PDP-1 was a machine with a separate timesharing system (did
it have a name?) and not an editor.

I had no exposure to ITS and so have no knowledge of its history
or the tools that it offered.  Was TECO truly its first editor?

I was exposed to the PDP-1 enough to play spacewar.  I recall
that prior to TECO it had an editor named Expensive Typewriter.
I never got to use that editor.

My reference to ITS and the PDP-1 was merely a conjecture
that if TECO did not originate the concept of point then it likely
inherited it from an early editor, most likely an editor running on
one of those two systems.

Some googling turned up this article in which Dan Murphy
mentions Expensive Typewriter and explains that TECO
originated on the PDP-1:

http://tenex.opost.com/anhc-31-4-anec.pdf

I also tracked down an Expensive Typewriter "manual":

http://archive.computerhistory.org/resources/text/DEC/pdp-1/DEC.pdp_1.1972.102650079.pdf

Reading that manual I can clearly see how Expensive
Typewriter gave rise to TECO.  That said ET was entirely
line-oriented.  I conclude that TECO first gave us the point
concept and terminology.

/john

Re: "Point" vs. "cursor" in documentation

[Eli Zaretskii]

> From: John Yates <john@yates-sheets.org>
> Date: Wed, 4 Jul 2018 08:13:22 -0400
> Cc: brandelune@gmail.com, Drew Adams <drew.adams@oracle.com>,
> 	Emacs developers <emacs-devel@gnu.org>
> 
> Similarly the PDP-1 was a machine with a separate timesharing system
> (did it have a name?)

I think you mean RSX-11, but there were others, see

  https://en.wikipedia.org/wiki/DEC_BATCH-11/DOS-11

RE: "Point" vs. "cursor" in documentation

[Drew Adams]

> I think you mean RSX-11

I remember it fondly.  Real-time processing, memory mapping - fun.

Re: "Point" vs. "cursor" in documentation

[Richard Stallman]

[[[ To any NSA and FBI agents reading my email: please consider    ]]]
[[[ whether defending the US Constitution against all enemies,     ]]]
[[[ foreign or domestic, requires you to follow Snowden's example. ]]]

  > I had no exposure to ITS and so have no knowledge of its history
  > or the tools that it offered.  Was TECO truly its first editor?

Yes.  PDP-10 TECO came before ITS.

The PDP-10 was an upward-compatible improvement of the PDP-6.
The AI lab first got a PDP-6 and wrote a TECO for it.

The PDP-6 was not suitable for timesharing.  So when it got the
PDP-10, people immediately used TECO on that too, but they also wrote
ITS.

-- 
Dr Richard Stallman
President, Free Software Foundation (https://gnu.org, https://fsf.org)
Internet Hall-of-Famer (https://internethalloffame.org)

Re: "Point" vs. "cursor" in documentation

[John ff]

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Athletes! The memories! I used ITS over the ARPANET, for access to macsyma.

So different from Titan's online system....

⁣Sent from Blue ​

On 4 Jul 2018, 23:33, at 23:33, Richard Stallman <rms@gnu.org> wrote:
>[[[ To any NSA and FBI agents reading my email: please consider    ]]]
>[[[ whether defending the US Constitution against all enemies,     ]]]
>[[[ foreign or domestic, requires you to follow Snowden's example. ]]]
>
>  > I had no exposure to ITS and so have no knowledge of its history
>  > or the tools that it offered.  Was TECO truly its first editor?
>
>Yes.  PDP-10 TECO came before ITS.
>
>The PDP-10 was an upward-compatible improvement of the PDP-6.
>The AI lab first got a PDP-6 and wrote a TECO for it.
>
>The PDP-6 was not suitable for timesharing.  So when it got the
>PDP-10, people immediately used TECO on that too, but they also wrote
>ITS.
>
>--
>Dr Richard Stallman
>President, Free Software Foundation (https://gnu.org, https://fsf.org)
>Internet Hall-of-Famer (https://internethalloffame.org)

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Re: "Point" vs. "cursor" in documentation

[Siraphob (Ben) Phipathananunth]

Right.  I've seen the explanation.  It's like hell|o where | is the position of point, and cursor appears over the "o".

When do we use point over cursor, and vice versa, in documentation?

Drew Adams wrote:
>> I've noticed usage of "the cursor" and "point" throughout manuals and
>> doc-strings.  In what context is one preferred over the other?
> 
> Point is the buffer position of the cursor (aka text cursor).
> 
> In the Emacs manual (`C-h r'), `i point' and `i cursor'
> both take you to node `Point', which explains this.
> 

-- 
Siraphob (Ben) Phipathananunth

Re: "Point" vs. "cursor" in documentation

[Stefan Monnier]

> When do we use point over cursor, and vice versa, in documentation?

"Point" is concerned about where operations will happen, whereas
"cursor" is concerned about where the thingy will be drawn on screen.
The cursor only moves when the display gets refreshed (i.e. once per
command, more or less), whereas point can be modified by lots of
intermediate operations, so it can change thousands of times within
a single command.


        Stefan

Re: "Point" vs. "cursor" in documentation

[Jean-Christophe Helary]

> On Jul 4, 2018, at 11:39, Stefan Monnier <monnier@iro.umontreal.ca> wrote:
> 
>> When do we use point over cursor, and vice versa, in documentation?
> 
> "Point" is concerned about where operations will happen, whereas
> "cursor" is concerned about where the thingy will be drawn on screen.
> The cursor only moves when the display gets refreshed (i.e. once per
> command, more or less), whereas point can be modified by lots of
> intermediate operations, so it can change thousands of times within
> a single command.

Which is the reason why "save-excursion" is used:

Introduction, 3.10

"In Emacs, a function frequently moves point as part of its internal workings even though a user would not expect this. For example, count-lines-region moves point. To prevent the user from being bothered by jumps that are both unexpected and (from the user’s point of view) unnecessary, save-excursion is often used to keep point in the location expected by the user. The use of save-excursion is good housekeeping."


Jean-Christophe Helary
-----------------------------------------------
http://mac4translators.blogspot.com @brandelune

RE: "Point" vs. "cursor" in documentation

[Drew Adams]

> Right.  I've seen the explanation.  It's like hell|o where | is the
> position of point, and cursor appears over the "o".
> 
> When do we use point over cursor, and vice versa, in documentation?

If the | is something visual, it indicates a position.
If it is the cursor then it indicates point.  That's
what the cursor does: it indicates the position (point)
where text is inserted when you type.

One (point) is the position.  The other (cursor) is
a visual indication of that position.  Even if the
cursor were removed (not displayed), point would be
there - it's just a buffer position (1 ...).

When you want to talk about the position where text
will be inserted etc., use "point".  When you want
to talk about the display artifact that indicates
that position (whether shown as bar, box, this color
or that), use "cursor".