setting non-user variables

setting non-user variables

[Héctor Lahoz]

Recently I upgraded my Emacs to version 24 (I don't like to live on
the edge :-) and noticed that I can't use set-variable to set
this buffer-local variable anymore. What should I do?
Why was this changed?

;; before I did:
;; set-variable RET mpkg-master-file RET "file.txt" RET
(make-variable-buffer-local
 (defvar mpkg-master-file))

Do I need an interactive command to set the variable?

(defun set-master-file (filename)
  (interative "fFilename: ")
  (setq mpkg-master-file filename))

Re: setting non-user variables

[Emanuel Berg]

"Héctor Lahoz" <hectorlahoz@gmail.com> writes:

> Recently I upgraded my Emacs to version 24 (I don't like to live on
> the edge :-) and noticed that I can't use set-variable to set
> this buffer-local variable anymore. What should I do?
> Why was this changed?
>
> ;; before I did:
> ;; set-variable RET mpkg-master-file RET "file.txt" RET
> (make-variable-buffer-local
>  (defvar mpkg-master-file))
>
> Do I need an interactive command to set the variable?
>
> (defun set-master-file (filename)
>   (interative "fFilename: ")
>   (setq mpkg-master-file filename))

... what? :)

Try

    (set-variable 'mpkg-master-file "file.txt" t)

with t as in MAKE-LOCAL.

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

Re: setting non-user variables

[Héctor Lahoz]

Emanuel Berg wrote:
> Try
> 
>     (set-variable 'mpkg-master-file "file.txt" t)
> 
> with t as in MAKE-LOCAL.
> 

What I meant is that I used set-variable interactively,
as M-x set-variable. Without LISP code.

Re: setting non-user variables

[Emanuel Berg]

Héctor Lahoz <hectorlahoz@gmail.com> writes:

>> Try
>> 
>>     (set-variable 'mpkg-master-file "file.txt" t)
>> 
>> with t as in MAKE-LOCAL.
>
> What I meant is that I used set-variable
> interactively, as M-x set-variable.
> Without LISP code.

Aha, then do C-u before you do M-x!

From the help

    (set-variable VARIABLE VALUE &optional MAKE-LOCAL)

    [...]
    
    With a prefix argument, set VARIABLE to VALUE
    buffer-locally.

So

    C-u M-x set-variable RET mpkg-master-file RET file.txt RET

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

Re: setting non-user variables

[Héctor Lahoz]

Emanuel Berg wrote:
> Héctor Lahoz <hectorlahoz@gmail.com> writes:
> 
> >> Try
> >> 
> >>     (set-variable 'mpkg-master-file "file.txt" t)
> >> 
> >> with t as in MAKE-LOCAL.
> >
> > What I meant is that I used set-variable
> > interactively, as M-x set-variable.
> > Without LISP code.
> 
> Aha, then do C-u before you do M-x!

Thanks, but the key is not "C-u". Either using
"C-u" or not, when I hit TAB it says "no match"
and I can't set the variable.

Re: setting non-user variables

[Emanuel Berg]

Héctor Lahoz <hectorlahoz@gmail.com> writes:

>> Aha, then do C-u before you do M-x!
>
> Thanks, but the key is not "C-u". Either using "C-u"
> or not, when I hit TAB it says "no match" and
> I can't set the variable.

C-u is `universal-argument'. You can try this for
example with C-u c

    cccc (4 c's)

or, C-u C-u c

    cccccccccccccccc (4**2 = 16 c's)

or, C-u C-u C-u c

    cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc
    (4**3 = 64 c's)

or, C-u 3 c

    ccc (3 c's)

and so on.

What you describe is because there isn't any
"mpkg-master-file" variable. So you either need to
load the mode programmatically with `require' or
`load', or go to a situation (state) in Emacs wich
implies it, "the mode" being whatever
module has the variable defined.

You can look for it with

    C-h v mpkg-master-file RET

is it there?

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

Re: setting non-user variables

[John Ankarström]

Héctor Lahoz <hectorlahoz@gmail.com> writes:

> What I meant is that I used set-variable interactively,
> as M-x set-variable. Without LISP code.

For this, I would use `customize-set-variable' - or,
`customize-variable' if you want the Customize GUI.

- John

Re: setting non-user variables

[John Ankarström]

john@ankarstrom.se (John Ankarström) writes:

> For this, I would use `customize-set-variable' - or,
> `customize-variable' if you want the Customize GUI.

Oh, sorry, I just reread your message, Héctor, and realized that
you want to set buffer-local variables. Please ignore my reply :-)

- John

Re: setting non-user variables

[Eli Zaretskii]

> From: "Héctor Lahoz" <hectorlahoz@gmail.com>
> Date: Wed, 31 May 2017 16:26:44 +0200
> 
> Recently I upgraded my Emacs to version 24 (I don't like to live on
> the edge :-) and noticed that I can't use set-variable to set
> this buffer-local variable anymore. What should I do?
> Why was this changed?
> 
> ;; before I did:
> ;; set-variable RET mpkg-master-file RET "file.txt" RET
> (make-variable-buffer-local
>  (defvar mpkg-master-file))

What package defines mpkg-master-file?  I couldn't find it in packages
bundled with Emacs.

Also, what version of Emacs did you have before the upgrade?

Re: setting non-user variables

[Héctor Lahoz]

Eli Zaretskii wrote:
> > From: "Héctor Lahoz" <hectorlahoz@gmail.com>
> > Date: Wed, 31 May 2017 16:26:44 +0200
> > 
> > Recently I upgraded my Emacs to version 24 (I don't like to live on
> > the edge :-) and noticed that I can't use set-variable to set
> > this buffer-local variable anymore. What should I do?
> > Why was this changed?
> > 
> > ;; before I did:
> > ;; set-variable RET mpkg-master-file RET "file.txt" RET
> > (make-variable-buffer-local
> >  (defvar mpkg-master-file))
> 
> What package defines mpkg-master-file?  I couldn't find it in packages
> bundled with Emacs.

It is my own. Not published yet.
 
> Also, what version of Emacs did you have before the upgrade?

23.4.1

So, to be clear. The variable is defined like this:

(make-variable-buffer-local
 (defvar mpkg-master-file nil
         "The path of the video associated to the current buffer"))

With 23 I could set the variable interactively, with 24 I can't.

Re: setting non-user variables

[tomas]

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On Thu, Jun 01, 2017 at 11:24:03AM +0200, Héctor Lahoz wrote:
> Eli Zaretskii wrote:
> > > From: "Héctor Lahoz" <hectorlahoz@gmail.com>
> > > Date: Wed, 31 May 2017 16:26:44 +0200
> > > 
> > > Recently I upgraded my Emacs to version 24 (I don't like to live on
> > > the edge :-) and noticed that I can't use set-variable to set
> > > this buffer-local variable anymore. What should I do?
> > > Why was this changed?
> > > 
> > > ;; before I did:
> > > ;; set-variable RET mpkg-master-file RET "file.txt" RET
> > > (make-variable-buffer-local
> > >  (defvar mpkg-master-file))
> > 
> > What package defines mpkg-master-file?  I couldn't find it in packages
> > bundled with Emacs.
> 
> It is my own. Not published yet.
>  
> > Also, what version of Emacs did you have before the upgrade?
> 
> 23.4.1
> 
> So, to be clear. The variable is defined like this:
> 
> (make-variable-buffer-local
>  (defvar mpkg-master-file nil
>          "The path of the video associated to the current buffer"))
> 
> With 23 I could set the variable interactively, with 24 I can't.

I can confirm that (Emacs 26.0.50 here). Variables defined through
defvar seem not to be indexed, whether buffer local or not. If you
use `defcustom', though, this will work:

  (defcustom mpkg-master-file nil "...")

No idea how that interacts with buffer-local though.

To me, it looks intentional. I'm a bit pressed now (should be doing
other things), but I'd expect it to be somewhere in the NEWS.

The nice thing about defcustom is that you get lots of options, like
for setting an edit widget for the value (and possibly some validation
code). The ugly thing is that you now get to read some docs ;-)

Cheers
- -- tomás
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RE: setting non-user variables

[Drew Adams]

> > (make-variable-buffer-local
> >  (defvar mpkg-master-file nil
> >          "The path of the video associated to the current buffer"))
> >
> > With 23 I could set the variable interactively, with 24 I can't.
> 
> I can confirm that (Emacs 26.0.50 here). Variables defined through
> defvar seem not to be indexed, whether buffer local or not. If you
> use `defcustom', though, this will work:
> 
>   (defcustom mpkg-master-file nil "...")

Yes, `set-variable' is for "user variables", aka user options,
only, aka symbols that satisfy predicate `user-variable-p'.

Today, that means a variable that is defined using defcustom,
or an alias to such a variable.

It USED to also mean any variable whose doc string begins with `*'.
Alas (IMHO), this feature was removed from Emacs 23 (i.e., long ago).

In Emacs 22 and prior you could do this:

(defvar foo  42 "*This is foo.")
(put 'foo 'variable-interactive "nWidth: ")

M-x set-variable foo RET

 Width: 13 RET

And `foo' was available for completion (e.g. `f TAB') using
`set-variable'.

Giving a variable a `variable-interactive' property tells
`set-variable' how to read a value for it.

Re: setting non-user variables

[tomas]

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On Thu, Jun 01, 2017 at 07:20:03AM -0700, Drew Adams wrote:

[...]

> Yes, `set-variable' is for "user variables", aka user options,
> only, aka symbols that satisfy predicate `user-variable-p'.
> 
> Today, that means a variable that is defined using defcustom,
> or an alias to such a variable.
> 
> It USED to also mean any variable whose doc string begins with `*'.
> Alas (IMHO), this feature was removed from Emacs 23 (i.e., long ago).

[...]

Thanks for the details. This makes my hunches more concrete
(without me having to look all that up: you're spoiling me :)

Cheers
- -- tomás
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Re: setting non-user variables

[Héctor Lahoz]

Drew Adams wrote:
> > > (make-variable-buffer-local
> > >  (defvar mpkg-master-file nil
> > >          "The path of the video associated to the current buffer"))
> > >
> > > With 23 I could set the variable interactively, with 24 I can't.
> > 
> > I can confirm that (Emacs 26.0.50 here). Variables defined through
> > defvar seem not to be indexed, whether buffer local or not. If you
> > use `defcustom', though, this will work:
> > 
> >   (defcustom mpkg-master-file nil "...")
> 
> Yes, `set-variable' is for "user variables", aka user options,
> only, aka symbols that satisfy predicate `user-variable-p'.
> 
> Today, that means a variable that is defined using defcustom,
> or an alias to such a variable.
> 
> It USED to also mean any variable whose doc string begins with `*'.
> Alas (IMHO), this feature was removed from Emacs 23 (i.e., long ago).
> 
> In Emacs 22 and prior you could do this:
> 
> (defvar foo  42 "*This is foo.")
> (put 'foo 'variable-interactive "nWidth: ")
> 
> M-x set-variable foo RET
> 
>  Width: 13 RET
> 
> And `foo' was available for completion (e.g. `f TAB') using
> `set-variable'.
> 
> Giving a variable a `variable-interactive' property tells
> `set-variable' how to read a value for it.
> 

You hit the nail on the head. In fact there is a "*" at the
beginning of the docstring and I was wondering why I put it
there some years ago.

Thanks a lot.