Lsp-mode: lsp-define-stdio-client deprecated?

[root42]

Describe the bug
The README.md of lsp-mode and several lsp-mode plugins state that one should use lsp-define-stdio-client to add new language servers. However I get the message "No op - only for backward compatibility.", which stems from lsp. el.

To Reproduce
Add something like this to your init.el:

     (lsp-define-stdio-client lsp-python "python"
                              #'projectile-project-root
                              '("pyls")) 

Expected behavior
The function lsp-python-enable would be generated.

Which Language Server did you use
lsp-python.

OS
Ubuntu 16.04 LTS

Error callstack
N/A

[yyoncho]

Please refer to https://github.com/emacs-lsp/lsp-mode/blob/master/README-NEXT.md and https://github.com/emacs-lsp/lsp-mode/issues/479 . We are in a process of deprecating lsp-mode.el. It is still usable, but once you require lsp.el you have to use only the lsp-mode NEXT stuff.

[root42]

Ok, so is this the new syntax then?

(lsp-register-client
 (make-lsp-client :new-connection (lsp-stdio-connection "pyls")
                  :major-modes '(python-mode)
                  :server-id 'pyls))

Maybe you should add a section "Upgrading from old lsp-mode versions" to the README then, also mention this in the old README.

[yyoncho]

Yes. As a side note, the pyls definition is part of lsp-clients.el and you no longer need additional packages for it along with several others languages.

[root42]

Ok, understood. But how do I then activate lsp in python-mode? I tried simply M-x lsp-mode, but all I get is LSP(disconnected) in the modeline.

[yyoncho]

Call lsp

[root42]

Then I get: user-error: Unable to find client(s) handling python-mode

[yyoncho]

as per README:

Some of the servers are directly supported by lsp-mode by requiring lsp-clients.el while other require installing additional package which provide server specific functionality.

[root42]

and to quote you:

Yes. As a side note, the pyls definition is part of lsp-clients.el and you no longer need additional packages for it along with several others languages.

So what is it then? Does python-mode now need some extra package + setup, or not? It's all quite confusing at the moment...

[yyoncho]

All the information is present in the readme I linked - there is a table in https://github.com/emacs-lsp/lsp-mode/blob/master/README-NEXT.md which lists what are the clients that are part of lsp-clients.el and what clients do require additional packages. It also lists what do you need to do to install the language server.

[root42]

Sorry, that really does not help. e.g. the table refers to cquery, which still lists old installation instructions. After the latest MELPA update lsp also broke cquery support. lsp-cquery-enable is not there anymore either, probably due to the same reason I filed this bug report in the first place. I still say you need to document an upgrade path for users of the old lsp mode. At the moment I have a broken installation where neither python nor cquery servers are working. And the README-NEXT.md says nothing about upgrading from older versions. For the time being I will try to downgrade to an older version of lsp-mode. Though not sure how to do it, since I never tried that.

[yyoncho]

To use the old version you should not require lsp.el but only lsp-mode.el. As you can see the cquery is marked as TBD - that means it is not ported to lsp.el. You could migrate to lsp.el once all of the clients that you are using are migrated to lsp.el.

[yyoncho]

Actually - cquery is using the new interface lsp.el. The only configuration to that you need to do is:

(require 'lsp-clients)
(require 'cquery)

(add-hook 'python-mode-hook 'lsp)
(add-hook 'c++-mode-hook 'lsp)

[root42]

I think I have cquery now running... I also realised that I was still triggering lsp-mode, instead of lsp upon entering programming-mode. So that is more or less fixed.
For cquery I simply removed the hook to lsp-cquery-enable. At least I can now manually enable lsp in c++-mode files.

[root42]

Thanks, that is pretty much what I did. :)

[jgarvin]

https://github.com/emacs-lsp/lsp-mode/blob/master/README-NEXT.md link is broken now is there a newer one?

[yyoncho]

@jgarvin it is moved in README.org (the home page of the REPO).