Re: master 2ec8f28: Introduce defcustom 'executable-prefix-env'

Re: master 2ec8f28: Introduce defcustom 'executable-prefix-env'

[Glenn Morris]

> branch: master
> commit 2ec8f28c59902ee1b533f9042c08f782422c2d86
> Author: Andrew L. Moore <slewsys@gmail.com>
> Commit: Eli Zaretskii <eliz@gnu.org>
>
>     Introduce defcustom 'executable-prefix-env'
[...]
>  (defcustom executable-prefix "#!"
> -  "Interpreter magic number prefix inserted when there was no magic number."
> -  :version "24.3"                       ; "#! " -> "#!"
> +  "Interpreter magic number prefix inserted when there was no magic number.
> +Use of `executable-prefix-env' is preferable to this option."
> +  :version "26.1"                       ; deprecated
>    :type 'string
>    :group 'executable)

I don't think I've seen a :version bump used for "not new and no change
in default, but deprecated". Normally such things are instead marked
obsolete.

Re: master 2ec8f28: Introduce defcustom 'executable-prefix-env'

[Eli Zaretskii]

> From: Glenn Morris <rgm@gnu.org>
> Date: Mon, 24 Jul 2017 11:58:43 -0400
> Cc: "Andrew L. Moore" <slewsys@gmail.com>
> 
> 
> >  (defcustom executable-prefix "#!"
> > -  "Interpreter magic number prefix inserted when there was no magic number."
> > -  :version "24.3"                       ; "#! " -> "#!"
> > +  "Interpreter magic number prefix inserted when there was no magic number.
> > +Use of `executable-prefix-env' is preferable to this option."
> > +  :version "26.1"                       ; deprecated
> >    :type 'string
> >    :group 'executable)
> 
> I don't think I've seen a :version bump used for "not new and no change
> in default, but deprecated".

But do you see anything wrong with doing that?  I didn't, so I left it
as submitted by the author.

Re: master 2ec8f28: Introduce defcustom 'executable-prefix-env'

[Glenn Morris]

Eli Zaretskii wrote:

>> I don't think I've seen a :version bump used for "not new and no change
>> in default, but deprecated".
>
> But do you see anything wrong with doing that?  I didn't, so I left it
> as submitted by the author.

It's not part of the documented meaning for :version ("This keyword
specifies that the item was first introduced in Emacs version VERSION,
or that its default value was changed in that version").

There's a standard method for deprecating options, to mark them
obsolete; so yes, I think using :version for that is wrong.

Re: master 2ec8f28: Introduce defcustom 'executable-prefix-env'

[Eli Zaretskii]

> From: Glenn Morris <rgm@gnu.org>
> Cc: emacs-devel@gnu.org,  slewsys@gmail.com
> Date: Wed, 26 Jul 2017 12:47:53 -0400
> 
> > But do you see anything wrong with doing that?  I didn't, so I left it
> > as submitted by the author.
> 
> It's not part of the documented meaning for :version ("This keyword
> specifies that the item was first introduced in Emacs version VERSION,
> or that its default value was changed in that version").

Yes, it's not the "usual" meaning, but it sounded close enough to me.

> There's a standard method for deprecating options, to mark them
> obsolete; so yes, I think using :version for that is wrong.

I don't think we should deprecate it in the normal sense of that word.

Re: master 2ec8f28: Introduce defcustom 'executable-prefix-env'

[Glenn Morris]

PS personally I don't see what was wrong with

(setq executable-prefix "#!/usr/bin/env ")'

http://lists.gnu.org/archive/html/emacs-devel/2017-06/msg00170.html

mentions safety concerns, but you always could, and still can, set it to
"#!/bin/rm " if you are so inclined. It's not even marked risky. But I
guess that would be pointless, since if someone could add a nasty
file-local setting, they could just directly add the #! line as well;
don't run scripts untrusted people can edit.

Re: master 2ec8f28: Introduce defcustom 'executable-prefix-env'

[Eli Zaretskii]

> From: Glenn Morris <rgm@gnu.org>
> Date: Mon, 24 Jul 2017 12:38:19 -0400
> Cc: "Andrew L. Moore" <slewsys@gmail.com>
> 
> 
> PS personally I don't see what was wrong with
> 
> (setq executable-prefix "#!/usr/bin/env ")'
> 
> http://lists.gnu.org/archive/html/emacs-devel/2017-06/msg00170.html
> 
> mentions safety concerns, but you always could, and still can, set it to
> "#!/bin/rm " if you are so inclined. It's not even marked risky. But I
> guess that would be pointless, since if someone could add a nasty
> file-local setting, they could just directly add the #! line as well;
> don't run scripts untrusted people can edit.

Thanks for the feedback.  I actually left the patch sitting tight for
more than a month, hoping to have comments, before I pushed it...

Re: master 2ec8f28: Introduce defcustom 'executable-prefix-env'

[Andrew L. Moore]

> On Jul 24, 2017, at 12:38 PM, Glenn Morris <rgm@gnu.org> wrote:
> 
> 
> PS personally I don't see what was wrong with
> 
> (setq executable-prefix "#!/usr/bin/env ")'
> 
> http://lists.gnu.org/archive/html/emacs-devel/2017-06/msg00170.html

Glenn,
If you're referring to the patch in it's original form, yes it’s more general,
but I agree with Eli that it’s pretty opaque.

Regarding “deprecation" of the variable `executable-prefix', there’s an argument
for not removing it:  the path of env (i.e., “/usr/bin/env”) is not universal.  On those
systems, the variable `executable-prefix’ would be a fallback.  And indeed, the
updated patch is written so that if the variable `executable-prefix’ is anything other
than “#!” or “#!/usr/bin/env”,  then it takes precedences over the value of
`executable-prefix-env’.

Okay, that explanation may be approaching opaque too, but if so, then let it be
another argument for simplicity over generality :)
-AM

> mentions safety concerns, but you always could, and still can, set it to
> "#!/bin/rm " if you are so inclined. It's not even marked risky. But I
> guess that would be pointless, since if someone could add a nasty
> file-local setting, they could just directly add the #! line as well;
> don't run scripts untrusted people can edit.