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 
address@hidden

Thanks,

Keith

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Begin forwarded message:

> From: Keith David Bershatsky <address@hidden>
> Date: March 4, 2016 3:16:56 PM PST
> To: Marcin Borkowski <address@hidden>
> Cc: address@hidden, John Wiegley <address@hidden>, Richard Stallman 
> <address@hidden>
> 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
> 
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> 
> 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