On 2/6/2022 8:42 AM, Max Nikulin wrote:
On 06/02/2022 01:27, Jim Porter wrote:
As a result, I think a good first step might be to add support for
"--funcall" to emacsclient, just like the regular emacs binary. (The
"-f" shorthand won't work though, since emacsclient already uses that
for "--server-file"). This would simplify the `message-mailto' case
above and would also allow org-protocol to do something similar:
emacsclient --funcall org-protocol-capture %u
No, --funcall is just a sugar for --eval '(func)' that does not contain
arbitrary input, but func has no access to other arguments and it is the
real problem.
Oh right, of course. The emacsclient case with `(message-mailto \"%u\")'
threw me off, but `message-mailto' works differently depending on
whether you pass it an arg or not.
I think, the solution is to add -arg command to emacs server protocol
that pushes its argument to a list and extend -exec command that would
make such list available as argv or as `command-line-args-left' for
evaluated expression. Of course, emacsclient option parser should be
modified as well to support --arg option
emacsclient --eval '(func)' --arg 1 2 3
emacsclient --eval '(func)' --arg -- 1 2 3
and maybe even for multiple eval+arg pairs
emacsclient --eval '(f1)' --arg 'a1' --eval '(f2)' --arg 'a2' 'a3'
I think something like this could work, so long as the arguments can be
forwarded correctly in the alternate editor case. If I understand how
emacsclient handles --eval, I think that might work, but it would still
require writing Lisp functions that know how to handle argv or
`command-line-args-left'. I'm also not totally sure how safe/sensible
that is when the arguments aren't from the invocation of emacs itself,
but from emacsclient (and thus, the args could be updated multiple times
throughout a session). It probably wouldn't actually break anything, but
it does seem a bit surprising to me...
Maybe another option would be to add an --apply argument that really
*does* consume the other command-line args and turns them into a
properly-quoted function call. Roughly speaking, it would turn this:
emacs --apply func foo bar baz
into this:
(apply #'func '(foo bar baz))
This would work effectively like how I momentarily thought --funcall
works. Then you could say:
emacsclient --apply org-protocol-capture %u
# or ...
emacs --apply org-protocol-capture %u
This would also mean that the `message-mailto' function from Gnus
doesn't need to care about `command-line-args-left' anymore, which would
simplify it somewhat. And this could be useful in general for
programmatically interacting with Emacs, since users would be able to
pass arbitrary strings to Emacs Lisp functions without having to worry
(as much) about sanitizing the strings first.
The proper place to discuss idea is emacs-devel list, but I am afraid
that without a patch it will be just buried.
I don't know if an actual patch would be a strict prerequisite for
posting to emacs-devel, but it's probably wise to have a clear, detailed
proposal first. I think it's easier to get everyone on board with an
idea if it's easy for them to see how all the details work up-front.
- Jim