Re: bug#22873: Can we support multiple Cursors?

Re: bug#22873: Can we support multiple Cursors?

[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. ]]]

  > What would be the added value of having that built-in vs. having it on
  > M?elpa?

Melpa and ELPA are totally different.

ELPA is effectively an extension of Emacs, and we refer users there.

Melpa is someone else's repository, which we cannot treat as part of
Emacs.  We do not steer users there.

-- 
Dr Richard Stallman
President, Free Software Foundation (gnu.org, fsf.org)
Internet Hall-of-Famer (internethalloffame.org)
Skype: No way! See stallman.org/skype.html.

Re: bug#22873: Can we support multiple Cursors?

[Marcin Borkowski]

On 2016-03-03, at 12:20, 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. ]]]
>
>   > What would be the added value of having that built-in vs. having it on
>   > M?elpa?
>
> Melpa and ELPA are totally different.
>
> ELPA is effectively an extension of Emacs, and we refer users there.
>
> Melpa is someone else's repository, which we cannot treat as part of
> Emacs.  We do not steer users there.

I understand all this.  (In fact, I wanted to write Elpa, only to
discover - to my surprise - that Magnar's multiple-cursors package is
actually on Melpa.  It is GPL'd, however.)

Still, I think that trying to implement that in core would be duplicated
effort, and the feature does not seem essential (it is roughly
equivalent to keyboard macros, though admittedly way cooler).  If
anything, I'd check whether it can be put on Elpa.

-- 
Marcin Borkowski
http://octd.wmi.amu.edu.pl/en/Marcin_Borkowski
Faculty of Mathematics and Computer Science
Adam Mickiewicz University

Re: bug#22873: Can we support multiple Cursors?

[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 understand all this.  (In fact, I wanted to write Elpa, only to
  > discover - to my surprise - that Magnar's multiple-cursors package is
  > actually on Melpa.  It is GPL'd, however.)

Would he / can he contribute it so we can put it in ELPA?

-- 
Dr Richard Stallman
President, Free Software Foundation (gnu.org, fsf.org)
Internet Hall-of-Famer (internethalloffame.org)
Skype: No way! See stallman.org/skype.html.

Re: bug#22873: Can we support multiple Cursors?

[Stefan Monnier]

>> I understand all this.  (In fact, I wanted to write Elpa, only to
>> discover - to my surprise - that Magnar's multiple-cursors package is
>> actually on Melpa.  It is GPL'd, however.)

> Would he / can he contribute it so we can put it in ELPA?

He already signed all the needed paperwork.  But there are probably
other contributors who haven't.


        Stefan

Re: bug#22873: Can we support multiple Cursors?

[Magnar Sveen]

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I'm pretty sure you don't want my multiple-cursors.el as an official
package. It's a major hack, basically trying to emulate the emacs command
loop in a post-command hook. After quite a lot of work, it now functions
properly for most commands - but it doesn't play so well in the presence of
other major hacks (like Evil).

I would say multiple cursors should be done properly if official.

Things that would help the multiple-cursors package, and also be a step
towards real support:

- allowing rendering of faux cursors. Right now I'm using inverted overlays
to create a block cursor (only).
- introduce the concept of cursor-local vars, much like buffer-local vars.
Right now I'm keeping track of a curated list of these in the package.
- document the inner workings of the command loop somewhere. This is what I
have right now:

(defun mc/execute-command (cmd)
  "Run command, simulating the parts of the command loop that makes sense
for fake cursors."
  (setq this-command cmd)
  (run-hooks 'pre-command-hook)
  (unless (eq this-command 'ignore)
    (call-interactively cmd))
  (run-hooks 'post-command-hook)
  (when deactivate-mark (deactivate-mark)))

I'm sure there's some nuance I'm missing, since there are still the odd
command that interacts oddly with it.

- Magnar


On Fri, Mar 4, 2016 at 3:59 PM Stefan Monnier <monnier@iro.umontreal.ca>
wrote:

> >> I understand all this.  (In fact, I wanted to write Elpa, only to
> >> discover - to my surprise - that Magnar's multiple-cursors package is
> >> actually on Melpa.  It is GPL'd, however.)
>
> > Would he / can he contribute it so we can put it in ELPA?
>
> He already signed all the needed paperwork.  But there are probably
> other contributors who haven't.
>
>
>         Stefan
>
>
>

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Re: bug#22873: Can we support multiple Cursors?

[Stefan Monnier]

> I'm pretty sure you don't want my multiple-cursors.el as an official
> package.

Being in GNU ELPA doesn't mean it's "official".  It does grant some kind
of respectability, but the main things it does is:
- make sure the code has a reliable license (usually, not a bug deal
  for the end user).
- make sure it can be installed out of the box without any extra customization.
- gets to be seen (and can be fixed) by Emacs's maintainers, so tends to
  follow the conventions a bit better.
- gets to be seen by whoever watches elpa-diffs, so might be ever so
  slightly less at risk of malware.
- gets to be seen by Emacs's maintainers so they may become aware of
  some issues that might require changes to the core.
...

> - allowing rendering of faux cursors. Right now I'm using inverted overlays
> to create a block cursor (only).

Seems like a good solution.  If this bumps into problems, we should
probably try and improve overlay support rather than try to add
specific "multi-cursor" support in the redisplay engine.

> (defun mc/execute-command (cmd)
>   "Run command, simulating the parts of the command loop that makes sense
> for fake cursors."
>   (setq this-command cmd)
>   (run-hooks 'pre-command-hook)
>   (unless (eq this-command 'ignore)
>     (call-interactively cmd))
>   (run-hooks 'post-command-hook)
>   (when deactivate-mark (deactivate-mark)))

FWIW, we could/should work to move execute-command as well as the
read-eval loop from C to Elisp.

Note that the above is "wrong" also in the sense that execute-command does
not run pre/post command hooks (this is done by the read-eval loop
instead, around the call to command-execute).


        Stefan

Re: bug#22873: Can we support multiple Cursors?

[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. ]]]

  > He already signed all the needed paperwork.  But there are probably
  > other contributors who haven't.

Could you talk with him about the situation?  Maybe we can
do without them.

-- 
Dr Richard Stallman
President, Free Software Foundation (gnu.org, fsf.org)
Internet Hall-of-Famer (internethalloffame.org)
Skype: No way! See stallman.org/skype.html.

Re: bug#22873: Can we support multiple Cursors?

[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. ]]]

  > Being in GNU ELPA doesn't mean it's "official".

It does, in some ways.  The packages in GNU ELPA are treated
mostly like part of Emacs, just distributed separately.

-- 
Dr Richard Stallman
President, Free Software Foundation (gnu.org, fsf.org)
Internet Hall-of-Famer (internethalloffame.org)
Skype: No way! See stallman.org/skype.html.

Re: bug#22873: Can we support multiple Cursors?

[John Wiegley]

>>>>> Stefan Monnier <monnier@iro.umontreal.ca> writes:

> FWIW, we could/should work to move execute-command as well as the read-eval
> loop from C to Elisp.

I would like to see that happen too, if it makes sense.

-- 
John Wiegley                  GPG fingerprint = 4710 CF98 AF9B 327B B80F
http://newartisans.com                          60E1 46C4 BD1A 7AC1 4BA2

Re: bug#22873: Can we support multiple Cursors?

[Clément Pit--Claudel]

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On 03/04/2016 09:16 PM, Stefan Monnier wrote:
>> > - allowing rendering of faux cursors. Right now I'm using inverted overlays
>> > to create a block cursor (only).
>
> Seems like a good solution.  If this bumps into problems, we should
> probably try and improve overlay support rather than try to add
> specific "multi-cursor" support in the redisplay engine.

It already bumps into problems: when you set your cursor to a bar and use use multiple cursors, only the real one actually looks like a bar.
Maybe we could add an overlay property to display a cursor at the left edge?
 


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Re: bug#22873: Can we support multiple Cursors?

[Clément Pit--Claudel]

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On 03/04/2016 05:18 PM, Magnar Sveen wrote:
> I'm sure there's some nuance I'm missing, since there are still the odd command that interacts oddly with it. 

Indeed: one such example is moving out of a composed region: secondary cursors (fake ones) move into prettified (composed) symbols, while the real cursor skips straight to the edges of composed regions.


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Re: bug#22873: Can we support multiple Cursors?

[Stefan Monnier]

>>> > - allowing rendering of faux cursors. Right now I'm using inverted
>>> > overlays to create a block cursor (only).
>> Seems like a good solution.  If this bumps into problems, we should
>> probably try and improve overlay support rather than try to add
>> specific "multi-cursor" support in the redisplay engine.
> It already bumps into problems: when you set your cursor to a bar and use
> use multiple cursors, only the real one actually looks like a bar.
> Maybe we could add an overlay property to display a cursor at the left edge?
 
Sounds like a fair solution.  Tho maybe it'd be even better to be able
to specify an overlay with a "bar cursor like thingy" regardless of what
kind of cursor is currently used.


        Stefan

Re: bug#22873: Can we support multiple Cursors?

[Stefan Monnier]

>> I'm sure there's some nuance I'm missing, since there are still the odd
>> command that interacts oddly with it. 

> Indeed: one such example is moving out of a composed region: secondary
> cursors (fake ones) move into prettified (composed) symbols, while the real
> cursor skips straight to the edges of composed regions.

Right: the adjust_point_for_property (in src/keyboard.c) functionality
should be exposed to Elisp.  It would be a part of a rewrite of the
read-eval loop.


        Stefan

Re: bug#22873: Can we support multiple Cursors?

[Keith David Bershatsky]

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Here is a duplicate copy of my recent e-mail and draft patch for the benefit of the emacs-devel@gnu.org

I will add emacs-devel@gnu.org to my list of automatic carbon-copy replies.

Thanks,

Keith

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Begin forwarded message:

> From: Keith David Bershatsky <esq@lawlist.com>
> Date: March 8, 2016 10:27:02 PM PST
> To: Marcin Borkowski <mbork@mbork.pl>, John Wiegley <jwiegley@gmail.com>, Richard Stallman <rms@gnu.org>
> Cc: 22873@debbugs.gnu.org
> Subject: Re: bug#22873: Can we support multiple Cursors?
> 
> The second draft of the proposed feature for multiple fake cursors is attached.  For the record, I'm not a programmer -- just a hobbyist -- and the draft patch is not meant to be a proposed official patch -- it is just a working proof concept.  The patch contains a few extra things that I use for debugging and also for drawing my solid vertical line that tracks the cursor position.  It has been tested to some extent on Emacs built for OSX 10.6.8 and Windows XP (SP-3).  Different colors for each fake cursor have already been implemented on Emacs for OSX, but I haven't yet looked into how to accomplish that objective on Emacs for Windows.  The draft concept patch is for the master branch as of March 8, 2016 bearing commit "e0400b72a24d67b53f71c8b97915cae599e36c37".  After applying the patch, the new feature can be tested as follows:
> 
> (defun mc-test (&optional list)
> "Draw fake cursors at all POS defined in the `mc-list'."
> (interactive)
>  (setq mc-list '(
>    (3 "hbar" [1.0 0.0 0.0])
>    (4 "bar" [0.0 1.0 0.0])
>    (5 "box" [0.0 0.0 1.0])
>    (6 "hollow" [1.0 1.0 1.0])
>    (7 ("hbar" 3) [1.0 0.0 1.0])
>    (8 ("bar" 3) [0.0 1.0 1.0]))))
> 
> (global-set-key [f1] 'mc-test)
> 
> To remove the cursors or change the cursors, just modify the buffer-local variable `mc-list' -- e.g., `(setq mc-list nil)` removes them all.  The colors on OSX are the standard RGB color vector.
> 
> Thank you, Marcin, for the referral to the ideit feature.  I will certainly try that feature out in the next few days, but have been buried in life's daily activities and also in acquiring the necessary skills to implement the fake cursors feature.
> 
> It sure would be great if a real programmer (instead of just a hobbyist like myself) could take this feature to the next level.  If the Windows setup is anything similar to OSX, implementing colors should not be that difficult to achieve (at least I hope that is the case).
> 
> I would like this feature to be similar to the original cursor such that a variable like `cursor-in-non-selected-windows' can be used to make the fake cursors displayed in only the selected window or in all windows where those points are visible.  At the present time, I've set it up so that only the selected window receives the fake cursors (as that is my personal preference).
> 
> Thank you for taking an interest in this potential new feature,
> 
> Keith
> 
> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
> 
> At Sat, 05 Mar 2016 07:59:52 +0100,
> Marcin Borkowski wrote:
>> 
>> * * *
>> 
>> Out of curiosity: did you try iedit?  How does it compare wrt speed in
>> such extreme cases?  (If it's applicable at all, that is - it's way
>> simpler than multiple-cursors, of course.)
> 

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Re: bug#22873: Can we support multiple Cursors?

[Keith David Bershatsky]

Here is a copy of my e-mail from last Friday that I forgot to send to emacs-devel@gnu.org

Thanks,

Keith

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Begin forwarded message:

> From: Keith David Bershatsky <esq@lawlist.com>
> Date: March 4, 2016 3:16:56 PM PST
> To: Marcin Borkowski <mbork@mbork.pl>
> Cc: 22873@debbugs.gnu.org, John Wiegley <jwiegley@gmail.com>, Richard Stallman <rms@gnu.org>
> Subject: Re: bug#22873: Can we support multiple Cursors?
> 
> I see this feature request as having two (2) distinct, yet related components.  The fake cursors being the first component that will operate similar to overlays, and are thus fairly innocuous as they won't have any real affect on where point is located after redisplay finishes.  The second component, however, is the functionality that can be found in Magnar Sveen's library and also is present in a popular commercial editor known as Sublime Text.
> 
> I enjoy using the multiple cursors library written by Magnar Sveen, but often find myself taking advantage of the wait times to pour myself a cup of coffee while making edits with a few hundred fake cursors in a large buffer.  E.g., I will type the word I want inserted or tap the arrow key a few times in a particular direction and then walk away from the computer or surf the web while Emacs does its thing.  I often have to use `M-x replace-string` when dealing with large numbers of edits instead of using my preferred choice of multiple cursors.  Admittedly, I am using a slightly older customized version of Mr. Sveen's library -- but I don't think the basic functionality has changed all that much since I first started using it.
> 
> I am not a programmer by trade, but I assume there could be some significant speed increases by having multiple cursor abilities baked into the C code base of the Emacs internals.
> 
> I don't think (based on my limited programming knowledge) that all of the cursor-types are presently available as overlays.  I need the left bar cursor so that I can draw my solid vertical line that tracks the cursor position, and so that is what motivated me to write a sample draft patch to the C internals.  My draft is progressing nicely, but it is slow to perfect because I am learning a few of the basics to the C language as I go.  I'll post to #22873 a revised draft of the first component (i.e., just fake cursors) in the next few days depending upon how many road blocks I encounter.  I've set up a simple cache of x/y/hpos/vpos so that recalculation is not necessary when the list of fake cursors doesn't change -- cursors are redrawn more than once per command loop depending upon what happens, e.g., with the mouse, etc.  And a user may not wish to change the positions of fake cursors every command loop, so the cache is helpful.
> 
> It may be a very long time, however, before I have enough basic skills to be able to implement some of the functionality of the second component.  I understand the implementation of feature 22873 is only a discussion at this point in time.  The beauty of Emacs, however, is that it's open source and I can make modifications to a custom build for my in-house use.  :)
> 
> Keith
> 
> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
> 
> At Thu, 03 Mar 2016 07:54:17 +0100,
> Marcin Borkowski wrote:
>> 
>> 
>> * * *
>> 
>> What would be the added value of having that built-in vs. having it on
>> M?elpa?
>> 
>> Best,
>> 
>> -- 
>> Marcin Borkowski