Policy for declaring safe local variable values

Policy for declaring safe local variable values

[Titus von der Malsburg]

I have a configuration variable (in package bibtex-completion) that can usefully be set to a local value via a ‘Local Variable‘ comment in the file.  E.g:

# Local Variables:
# bibtex-completion-bibliography: "/path/to/bibliography.bib"
# End:

However, it’s annoying that users have to confirm that the local value for this variable is safe every time they open a file with a different value for that variable.  Question: Can I declare the variable safe for local values in my package, e.g.

(put 'bibtex-completion-bibliography 'safe-local-variable (lambda (_) t))

or would that violate Emacs conventions?

  Titus

Re: Policy for declaring safe local variable values

[Joost Kremers]

On Fri, Oct 08 2021, Titus von der Malsburg wrote:
> I have a configuration variable (in package bibtex-completion) that can usefully be set to a local value via a ‘Local Variable‘ comment in the file.  E.g:
>
> # Local Variables:
> # bibtex-completion-bibliography: "/path/to/bibliography.bib"
> # End:
>
> However, it’s annoying that users have to confirm that the local value for this
> variable is safe every time they open a file with a different value for that
> variable.

Fun fact: answering your e-mail in Emacs I got the same question. :-)

> Question: Can I declare the variable safe for local values in my
> package, e.g.
>
> (put 'bibtex-completion-bibliography 'safe-local-variable (lambda (_) t))
>
> or would that violate Emacs conventions?

`defcustom` even has a keyword for it (`:safe`), so I don't think it violates
any conventions.

TBH, I use this method in some of my packages and it never occurred to me it
might be against conventions...

-- 
Joost Kremers
Life has its moments

Re: Policy for declaring safe local variable values

[Lars Ingebrigtsen]

Titus von der Malsburg <malsburg@posteo.de> writes:

> (put 'bibtex-completion-bibliography 'safe-local-variable (lambda (_) t))
>
> or would that violate Emacs conventions?

I think that's fine, but use `stringp' instead.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

Re: Policy for declaring safe local variable values

[Titus von der Malsburg]

On 2021-10-08 Fri 11:55, Joost Kremers <joostkremers@fastmail.fm> wrote:
> On Fri, Oct 08 2021, Titus von der Malsburg wrote:
>> I have a configuration variable (in package bibtex-completion) that can usefully be set to a local value via a ‘Local Variable‘ comment in the file.  E.g:
>>
>> # Local Variables:
>> # bibtex-completion-bibliography: "/path/to/bibliography.bib"
>> # End:
>>
>> However, it’s annoying that users have to confirm that the local value for this
>> variable is safe every time they open a file with a different value for that
>> variable.
>
> Fun fact: answering your e-mail in Emacs I got the same question. :-)

This is scary and perhaps even a bug?  It seems wrong that text in e-mails should be allowed to set local variables.

>> Question: Can I declare the variable safe for local values in my
>> package, e.g.
>>
>> (put 'bibtex-completion-bibliography 'safe-local-variable (lambda (_) t))
>>
>> or would that violate Emacs conventions?
>
> `defcustom` even has a keyword for it (`:safe`), so I don't think it violates
> any conventions.
>
> TBH, I use this method in some of my packages and it never occurred to me it
> might be against conventions...

Thank you.  I wasn’t aware of the ‘:safe‘ keyword.

  Titus

Re: Policy for declaring safe local variable values

[Joost Kremers]

On Fri, Oct 08 2021, Titus von der Malsburg wrote:
>> Fun fact: answering your e-mail in Emacs I got the same question. :-)
>
> This is scary and perhaps even a bug? It seems wrong that text in e-mails should
> be allowed to set local variables.

You might be right.

>> `defcustom` even has a keyword for it (`:safe`), so I don't think it violates
>> any conventions.
>>
>> TBH, I use this method in some of my packages and it never occurred to me it
>> might be against conventions...
>
> Thank you.  I wasn’t aware of the ‘:safe‘ keyword.

Note that the Elisp manual says that using `:safe` has a disadvantage and that
an autoload cookie may be a better solution (scroll down a little or search for
"autoload"):

(info "(elisp) File Local Variables")



-- 
Joost Kremers
Life has its moments