Notify region-extract-function change in NEWS?

Notify region-extract-function change in NEWS?

[Kaushal Modi]

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Hi all,

I do not know if a change to the default value of region-extract-function
is supposed to be put in the NEWS; especially because it's a defvar, not a
defcustom.

But that change broke my config because I was tweaking the value of
region-extract-function.

Commit that changes the default value of region-extract-function:
http://git.savannah.gnu.org/cgit/emacs.git/diff/lisp/simple.el?h=emacs-25&id=31f6e939334180add7bc11240343615a2e6350f6

Here is the associated change I needed in my config:
https://github.com/kaushalmodi/.emacs.d/commit/ae38531ca5fb51d4b3303face4c5103ed4f70b3b

I need to update the region-extract-function because I want to add C-u
functionality to C-w/M-w. (Please advise if there's a better way to do
that.)

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Re: Notify region-extract-function change in NEWS?

[Kaushal Modi]

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You can probably ignore this.. at least on github, not many people are
tweaking this variable:
https://github.com/search?utf8=%E2%9C%93&q=extension%3Ael+%22setq+region+extract+function%22

:P

On Fri, Feb 5, 2016 at 3:29 PM Kaushal Modi <kaushal.modi@gmail.com> wrote:

> Hi all,
>
> I do not know if a change to the default value of region-extract-function
> is supposed to be put in the NEWS; especially because it's a defvar, not a
> defcustom.
>
> But that change broke my config because I was tweaking the value of
> region-extract-function.
>
> Commit that changes the default value of region-extract-function:
> http://git.savannah.gnu.org/cgit/emacs.git/diff/lisp/simple.el?h=emacs-25&id=31f6e939334180add7bc11240343615a2e6350f6
>
> Here is the associated change I needed in my config:
> https://github.com/kaushalmodi/.emacs.d/commit/ae38531ca5fb51d4b3303face4c5103ed4f70b3b
>
> I need to update the region-extract-function because I want to add C-u
> functionality to C-w/M-w. (Please advise if there's a better way to do
> that.)
>

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Re: Notify region-extract-function change in NEWS?

[Juri Linkov]

> (Please advise if there's a better way to do that.)

A better way to do that is to override the default value of
region-extract-function using add-function.
You could find some examples of add-function usages in
http://git.savannah.gnu.org/cgit/emacs.git/commit/?h=emacs-25&id=31f6e939334180add7bc11240343615a2e6350f6

Re: Notify region-extract-function change in NEWS?

[Kaushal Modi]

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Thanks Juri.

On Fri, Feb 5, 2016 at 8:13 PM Juri Linkov <juri@linkov.net> wrote:

> A better way to do that is to override the default value of
> region-extract-function using add-function.
> You could find some examples of add-function usages in
>
> http://git.savannah.gnu.org/cgit/emacs.git/commit/?h=emacs-25&id=31f6e939334180add7bc11240343615a2e6350f6


I have reimplemented my earlier redefinition of region-extract-function
using add-function:
https://github.com/kaushalmodi/.emacs.d/blob/78ed92f384bac8ef2f3a4ec2faf61a21814475cd/setup-files/setup-editing.el#L744-L766

and it seems to work fine as before, but with lesser lines of code! :)

So just to be clear, using add-function makes the region-extract-function
tweaks a bit concise. But I would still need to update this if and when the
region-extract-function default value changes in future. For instance, here
I needed to have the "(not (eq delete 'bounds))" condition to match what
was recently added to that var.

Kaushal

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Re: Notify region-extract-function change in NEWS?

[Kaushal Modi]

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I believe I was doing a bit wrong earlier; it's fixed now (
https://github.com/kaushalmodi/.emacs.d/commit/822854333cd2cc05c2b4cfe642925f832cf40cfb
 ).

=====

(defun modi/region-extract-function--C-u-kill (orig delete)
  "When a region is selected,
and if \\[universal-argument] is used,
and DELETE is \\='delete (when doing \\[kill-region]), or
    DELETE is nil (when doing \\[kill-ring-save]),
kill the region with all trailing whitespace removed and also replace 2
or more spaces with single spaces.
Else, execute ORIG function."
  (if (and (region-beginning)
           (eq 4 (prefix-numeric-value current-prefix-arg)) ; when using
C-u, and
           (or (eq delete 'delete) ; when cutting (C-w), or
               (eq delete nil))) ; when copying (M-w)
      (let ((sel (filter-buffer-substring (region-beginning) (region-end)
delete)))
        (with-temp-buffer
          (insert sel)
          (delete-trailing-whitespace)
          (goto-char (point-min))
          (while (re-search-forward "\\s-\\{2,\\}" nil :noerror)
            (replace-match " "))
          (buffer-string)))
    (funcall orig delete)))
(add-function :around region-extract-function
#'modi/region-extract-function--C-u-kill)

=====

So now it is probably more immune to future changes to the default value of
region-extract-function. Thanks for the tip to look into add-function.

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Re: Notify region-extract-function change in NEWS?

[Stefan Monnier]

> I need to update the region-extract-function because I want to add C-u
> functionality to C-w/M-w. (Please advise if there's a better way to do
> that.)

Don't use setq on *-function.  Instead, use add-function or remove-function.


        Stefan

Re: Notify region-extract-function change in NEWS?

[John Wiegley]

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

>> I need to update the region-extract-function because I want to add C-u
>> functionality to C-w/M-w. (Please advise if there's a better way to do
>> that.)

> Don't use setq on *-function. Instead, use add-function or remove-function.

The subtle pun in your answer did not go unappreciated. :)

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