clear-kill-ring function

clear-kill-ring function

[Sharon Kimble]

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For a long time I have wanted to have some way of clearing the
kill-ring, and I have recently started using the "cliphist" package,
like this -

--8<---------------cut here---------------start------------->8---
#+begin_src emacs-lisp
(require 'cliphist)
(global-set-key (kbd "s-,") 'cliphist-select-item)
(global-set-key (kbd "s-.") 'cliphist-paste-item)
#+end_src
--8<---------------cut here---------------end--------------->8---

which is working very well to use data from "parcellite".

And I seem to have found a way of clearing the kill-ring, at http://qdot.github.io/conf_emacs/

--8<---------------cut here---------------start------------->8---
#+begin_src emacs-lisp
(defun qdot/clear-kill-ring ()
  "Clear the kill ring variable"
  (setq kill-ring nil))
(global-set-key (kbd "s-/") 'qdot/clear-kill-ring)
#+end_src
--8<---------------cut here---------------end--------------->8---

However when I do "s-/" emacs replied with

╭────
│(wrong-type-argument commandp qdot/clear-kill-ring) in ad-Advice-call-interactively
╰────

So what should I have in my function please to get it working properly?

Thanks
Sharon.
-- 
A taste of linux = http://www.sharons.org.uk
TGmeds = http://www.tgmeds.org.uk
Debian 8.0, fluxbox 1.3.7, emacs 24.5.1

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Re: clear-kill-ring function

[Barry Margolin]

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In article <mailman.1159.1445970298.7904.help-gnu-emacs@gnu.org>,
 Sharon Kimble <boudiccas@skimble.plus.com> wrote:

> --8<---------------cut here---------------start------------->8---
> #+begin_src emacs-lisp
> (defun qdot/clear-kill-ring ()
>   "Clear the kill ring variable"
>   (setq kill-ring nil))
> (global-set-key (kbd "s-/") 'qdot/clear-kill-ring)
> #+end_src
> --8<---------------cut here---------------end--------------->8---
> 
> However when I do "s-/" emacs replied with
> 
> ¢~¢w¢w¢w¢w
> ¢x(wrong-type-argument commandp qdot/clear-kill-ring) in 
> ad-Advice-call-interactively
> ¢¢¢w¢w¢w¢w
> 
> So what should I have in my function please to get it working properly?

You forgot to put (interactive) in qdot/clear-kill-ring, to indicate 
that it's a command, not just an ordinary function.

-- 
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***

Re: clear-kill-ring function

[Sharon Kimble]

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Barry Margolin <barmar@alum.mit.edu> writes:

> In article <mailman.1159.1445970298.7904.help-gnu-emacs@gnu.org>,
>  Sharon Kimble <boudiccas@skimble.plus.com> wrote:
>
>> --8<---------------cut here---------------start------------->8---
>> #+begin_src emacs-lisp
>> (defun qdot/clear-kill-ring ()
>>   "Clear the kill ring variable"
>>   (setq kill-ring nil))
>> (global-set-key (kbd "s-/") 'qdot/clear-kill-ring)
>> #+end_src
>> --8<---------------cut here---------------end--------------->8---
>> 
>> However when I do "s-/" emacs replied with
>> 
>> ¢~¢w¢w¢w¢w
>> ¢x(wrong-type-argument commandp qdot/clear-kill-ring) in 
>> ad-Advice-call-interactively
>> ¢¢¢w¢w¢w¢w
>> 
>> So what should I have in my function please to get it working properly?
>
> You forgot to put (interactive) in qdot/clear-kill-ring, to indicate 
> that it's a command, not just an ordinary function.

You mean like -

╭────
│(defun qdot/clear-kill-ring (interactive)
╰────

I'm not sure what you mean or how to show it. Is that what you meant?

Thanks
Sharon.
-- 
A taste of linux = http://www.sharons.org.uk
TGmeds = http://www.tgmeds.org.uk
Debian 8.0, fluxbox 1.3.7, emacs 24.5.1

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Re: clear-kill-ring function

[Michael Heerdegen]

Sharon Kimble <boudiccas@skimble.plus.com> writes:

> You mean like -
>
> ╭────
> │(defun qdot/clear-kill-ring (interactive)
> ╰────

More like

  (defun qdot/clear-kill-ring ()
    (interactive)
    ...)

See (info "(elisp) Using Interactive").


Michael.

Re: clear-kill-ring function

[Emanuel Berg]

Sharon Kimble <boudiccas@skimble.plus.com> writes:

> (defun qdot/clear-kill-ring (interactive)
>
> I'm not sure what you mean or how to show it.
> Is that what you meant?

You put (interactive) after the parameter list (the
argument names), which is empty in your case so should
be the empty list, ().

An interactive function is a "command", which means
you can invoke it from M-x and also bind it to a key.

There are situations where you can have the same
function behave differently when called from Elisp
(i.e., invoked from another piece of code) compared to
when it is used interactively (again, with M-x or
a keystroke bound to that function) - however, as for
me, I don't see a great value in this distinction and
has only rarely used it. Perhaps someone who disagrees
will explain why it is there and what benefits
it brings.

Note that you can invoke non-interactive functions
with `eval-expr' (or `M-:') so it is not like they are
inaccessible to the "interactive" user. (They will
execute noninteractively still, of course.)

-- 
underground experts united
http://user.it.uu.se/~embe8573

Re: clear-kill-ring function

[Sharon Kimble]

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Michael Heerdegen <michael_heerdegen@web.de> writes:

> Sharon Kimble <boudiccas@skimble.plus.com> writes:
>
>> You mean like -
>>
>> ╭────
>> │(defun qdot/clear-kill-ring (interactive)
>> ╰────
>
> More like
>
>   (defun qdot/clear-kill-ring ()
>     (interactive)
>     ...)
>
> See (info "(elisp) Using Interactive").

Thanks for this Michael, I now have -

--8<---------------cut here---------------start------------->8---
#+begin_src emacs-lisp
(defun clear-kill-ring ()
(interactive)
  "Clear the kill ring variable"
  (setq kill-ring nil))
(global-set-key (kbd "s-/") 'clear-kill-ring)
#+end_src
--8<---------------cut here---------------end--------------->8---

And have restarted emacs several times, but if I do a "s-." before hand
I can see several items on the kill-ring. So I then do "s-/" to clear
the kill-ring, and if I then do a further "s-." it shows that there
still remains the same items on the kill-ring, i.e. nothing has changed!
Or, IOW, the function isn't working!

So I'm back to my original question, what do I have to do to get it
working please?

Thanks
Sharon.
-- 
A taste of linux = http://www.sharons.org.uk
TGmeds = http://www.tgmeds.org.uk
Debian 8.0, fluxbox 1.3.7, emacs 24.5.1

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Re: clear-kill-ring function

[Joost Kremers]

Sharon Kimble wrote:
>=2D-8<---------------cut here---------------start------------->8---
> #+begin_src emacs-lisp
> (defun clear-kill-ring ()
> (interactive)
>   "Clear the kill ring variable"
>   (setq kill-ring nil))
> (global-set-key (kbd "s-/") 'clear-kill-ring)
> #+end_src
>=2D-8<---------------cut here---------------end--------------->8---

Note that the doc string should go before the (interactive) call:

```
(defun clear-kill-ring ()
  "Clear the kill ring variable"
  (interactive)
  (setq kill-ring nil))
(global-set-key (kbd "s-/") 'clear-kill-ring)
```

> And have restarted emacs several times, but if I do a "s-." before hand
> I can see several items on the kill-ring. So I then do "s-/" to clear
> the kill-ring, and if I then do a further "s-." it shows that there
> still remains the same items on the kill-ring, i.e. nothing has changed!
> Or, IOW, the function isn't working!

It probably is. Assuming that you have `s-.` bound to
`cliphist-paste-item` as in your original post, hitting `s-.` will
(presumably; I don't know cliphist) populate the kill ring with the
items in the clipboard history. Emtpying the Emacs kill ring doesn't
change the clipboard history, because they're two different things.

To see the contents of the kill ring, you can evaluate the variable
`kill-ring` in the *scratch* buffer (put `kill-ring` on a separate line
and hit C-j). Or use `C-h v kill-ring RET`.

There's also the packge `browse-kill-ring`, which shows the contents of
the kill ring in a separate buffer and allows you to pick any item to
paste.

HTH

-- 
Joost Kremers                                   joostkremers@fastmail.fm
Selbst in die Unterwelt dringt durch Spalten Licht
EN:SiS(9)

Re: clear-kill-ring function

[Michael Heerdegen]

Joost Kremers <joost.m.kremers@gmail.com> writes:

> (defun clear-kill-ring ()
>   "Clear the kill ring variable"
>   (interactive)
>   (setq kill-ring nil))
> (global-set-key (kbd "s-/") 'clear-kill-ring)

It's more consistent to also reset the yank pointer:

(defun clear-kill-ring ()
  "Clear the kill ring variable"
  (interactive)
  (setq kill-ring nil
        kill-ring-yank-pointer nil))

> > Or, IOW, the function isn't working!
>
> It probably is.

Indeed, it is.


Michael.

Re: clear-kill-ring function

[Emanuel Berg]

Joost Kremers <joost.m.kremers@gmail.com> writes:

> Note that the doc string should go before the
> (interactive) call ...
>
>    "Clear the kill ring variable"

Docstrings should be either all user-oriented or all
technology ditto. Or both, in different paragraphs.

In general I'd say user-oriented is much better,
especially in the context of an Emacs help screen and
an interactive function, like what we have here.

However, despite being interactive, this function is
all about technology which might motivate some
tech material.

So either

    "Discard all killed text."

or

    "Set `kill-ring' and `kill-ring-yank-pointer'
    to nil."

Or both:

    "Discard all killed text.\n\nI.e., set `kill-ring' and `kill-ring-yank-pointer' to nil."

As for "Clear the kill ring variable":

    1. It only explains what happens in terms of
       technology, not why anyone would do that or
       what is gained from a user perspective by doing
       it. (Here, there purpose is unclear - why would
       anyone do this? - perhaps the OP can explain
       the gain of having an interactive function
       do this.)

    2. There are many "kill ring" variables:

           kill-ring
           kill-ring-max
           kill-ring-yank-pointer

       Which one exactly? And if there is a mention of
       a variable, why not give the exact name and put
       it within `whatever' to make it hyperlinked?

    3. `kill-ring-max' is an integer, while
       `kill-ring' and `kill-ring-yank-pointer' are or
       leads to complicated data structures.
       What exactly does "clear" mean? 0, nil, or an
       empty data structure?

-- 
underground experts united
http://user.it.uu.se/~embe8573