Re: master 43fded1: Add lisp-data-mode for editing non-code Lisp data

Re: master 43fded1: Add lisp-data-mode for editing non-code Lisp data

[Michael Albinus]

João Távora <joaotavora@gmail.com> writes:

Hi João,

> diff --git a/lisp/net/tramp-cache.el b/lisp/net/tramp-cache.el
> index 09e30f0..6d87ce2 100644
> --- a/lisp/net/tramp-cache.el
> +++ b/lisp/net/tramp-cache.el
> @@ -472,7 +472,7 @@ used to cache connection properties of the local machine."
>  	;; Dump it.
>  	(with-temp-file tramp-persistency-file-name
>  	  (insert
> -	   ";; -*- emacs-lisp -*-"
> +	   ";; -*- lisp-data -*-"
>  	   ;; `time-stamp-string' might not exist in all Emacs flavors.
>  	   (condition-case nil
>  	       (progn

That's a problem. Tramp must be backward compatible with Emacs 25 and
later, which doesn't know of lisp-data-mode. Could you, pls, revert this
part of your commit?

Best regards, Michael.

Re: master 43fded1: Add lisp-data-mode for editing non-code Lisp data

[Stefan Monnier]

>> -	   ";; -*- emacs-lisp -*-"
>> +	   ";; -*- lisp-data -*-"
[...]
> That's a problem.  Tramp must be backward compatible with Emacs 25 and
> later, which doesn't know of lisp-data-mode.  Could you, pls, revert this
> part of your commit?

[ Do we also care about writing this file from Emacs-28 and then
  reading it in Emacs-25?  How 'bout restricting it so you can only use
  it with Emacs-25-but-using-a-recent-Tramp?  ]
[ Also, I assume the above problem appears because Tramp uses
  `find-file-noselect` to access this file, so it could be fixed by
  making it use `insert-file-contents` instead, right?  ]

Reminds me of similar problems I've encountered with files where I want
to use some home-made derived major mode and where they then fail
miserably when used without the rest of my config.

Clearly it's too late to fix the above problem with Emacs-25, but for
the future, I think we should provide a way to specify not just a single
mode but a list of modes by order of preference, so if `lisp-data` is
not available it falls back to `emacs-liso`.


        Stefan

Re: master 43fded1: Add lisp-data-mode for editing non-code Lisp data

[Michael Albinus]

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

Hi Stefan,

>> That's a problem.  Tramp must be backward compatible with Emacs 25 and
>> later, which doesn't know of lisp-data-mode.  Could you, pls, revert this
>> part of your commit?
>
> [ Do we also care about writing this file from Emacs-28 and then
>   reading it in Emacs-25?  How 'bout restricting it so you can only use
>   it with Emacs-25-but-using-a-recent-Tramp?  ]

Yes, we care. And no, I don't see a reason to restrict ourselves; using
lisp-data-mode in that file is not super important.

> [ Also, I assume the above problem appears because Tramp uses
>   `find-file-noselect` to access this file, so it could be fixed by
>   making it use `insert-file-contents` instead, right?  ]

It is not a problem reading the file in Tramp code; Tramp uses already
`insert-file-contents-literally`. The problem is rather when you want to
visit the file interactively in a buffer.

>         Stefan

Best regards, Michael.

Re: master 43fded1: Add lisp-data-mode for editing non-code Lisp data

[João Távora]

On Sat, May 2, 2020 at 11:32 AM Michael Albinus <michael.albinus@gmx.de> wrote:
>
> Stefan Monnier <monnier@iro.umontreal.ca> writes:

> It is not a problem reading the file in Tramp code; Tramp uses already
> `insert-file-contents-literally`. The problem is rather when you want to
> visit the file interactively in a buffer.

I think what Stefan is saying is that the probability that you are going
to use Emacs <28 to visit a file produced by Emacs 28 is low.  And the
adverse effects are an error message that I personally could live with
on those (presumably rare) occasions.
FWIW I think of lisp-data-mode as most useful in non-Emacs produced
files (i.e. complex data files produced by Lisp-y applications).

Anyway, haven't reverted it yet, but have no problem in doing so.
And won't mind if you beat me to it.

João

Re: master 43fded1: Add lisp-data-mode for editing non-code Lisp data

[Michael Albinus]

João Távora <joaotavora@gmail.com> writes:

Hi João,

> I think what Stefan is saying is that the probability that you are going
> to use Emacs <28 to visit a file produced by Emacs 28 is low.  And the
> adverse effects are an error message that I personally could live with
> on those (presumably rare) occasions.

At least I do it daily :-)

And the problem is not the error message. The emacs-lisp cookie is there
for a reason; I want to get syntax highlighting in that file.

> João

Best regards, Michael.

Re: master 43fded1: Add lisp-data-mode for editing non-code Lisp data

[João Távora]

On Sat, May 2, 2020 at 12:20 PM Michael Albinus <michael.albinus@gmx.de> wrote:
>
> João Távora <joaotavora@gmail.com> writes:
>
> Hi João,
>
> > I think what Stefan is saying is that the probability that you are going
> > to use Emacs <28 to visit a file produced by Emacs 28 is low.  And the
> > adverse effects are an error message that I personally could live with
> > on those (presumably rare) occasions.
>
> At least I do it daily :-)

Makes sense to disable it, in that case.

Re: master 43fded1: Add lisp-data-mode for editing non-code Lisp data

[Stefan Monnier]

> It is not a problem reading the file in Tramp code; Tramp uses already
> `insert-file-contents-literally`. The problem is rather when you want to
> visit the file interactively in a buffer.

Thanks for clarifying.

IIUC you may want to visit that file even with an Emacs that doesn't
support Tramp at all, right?
So the "backward compatibility" desired here is not directly connected
to the backward compatibility needed for Tramp itself, right?


        Stefan

Re: master 43fded1: Add lisp-data-mode for editing non-code Lisp data

[Michael Albinus]

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

> IIUC you may want to visit that file even with an Emacs that doesn't
> support Tramp at all, right?

In theory, yes. In practice, it won't happen. Emacs supports Tramp since
release 22 out-of-the-box.

>         Stefan

Best regards, Michael.

Re: master 43fded1: Add lisp-data-mode for editing non-code Lisp data

[João Távora]

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On Fri, May 1, 2020, 18:52 Michael Albinus <michael.albinus@gmx.de> wrote:

> João Távora <joaotavora@gmail.com> writes:
>
> Hi João,
>
> > diff --git a/lisp/net/tramp-cache.el b/lisp/net/tramp-cache.el
> > index 09e30f0..6d87ce2 100644
> > --- a/lisp/net/tramp-cache.el
> > +++ b/lisp/net/tramp-cache.el
> > @@ -472,7 +472,7 @@ used to cache connection properties of the local
> machine."
> >       ;; Dump it.
> >       (with-temp-file tramp-persistency-file-name
> >         (insert
> > -        ";; -*- emacs-lisp -*-"
> > +        ";; -*- lisp-data -*-"
> >          ;; `time-stamp-string' might not exist in all Emacs flavors.
> >          (condition-case nil
> >              (progn
>
> That's a problem. Tramp must be backward compatible with Emacs 25 and
> later, which doesn't know of lisp-data-mode. Could you, pls, revert this
> part of your commit?
>

No problem.  Will do so asap.

João

>

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Re: master 43fded1: Add lisp-data-mode for editing non-code Lisp data

[Michael Albinus]

João Távora <joaotavora@gmail.com> writes:

>     That's a problem. Tramp must be backward compatible with Emacs 25
>     and later, which doesn't know of lisp-data-mode. Could you, pls,
>     revert this part of your commit?
>
> No problem.  Will do so asap.

I've done that, adding also a comment that we could use the lisp-data
cookie once we support only Emacs 28 or higher.

> João

Best regards, Michael.