Support settings options for pyls

[w0rp]

As with many other options, add an ale_python_pyls_options variable for defining options for pyls, with documentation and tests.

[andrewminer]

According to the folks over at Palantir (palantir/python-language-server#312), this needs to be done by sending a workspace/didChangeConfiguration message to pyls once it has been started. This will allow you to configure which linters are used.

[w0rp]

Okay, makes sense. I imagine this will come up for a few different LSP servers. What we ought to do is implement variables like g:ale_<filetype>_<linter_name>_settings, and an option for ale#linter#Define for calling a function to get settings for an LSP linter. That way we can implement some fixed settings for an LSP linter, or some dynamic settings for them. I think you can also pass the settings to an LSP server in an initial message, but workspace/didChangeConfiguration will work too.

[etaoins]

This is useful for RLS as well: https://github.com/rust-lang-nursery/rls#configuration

[eugene-bright]

#1852 is merged.
Will the options below take effect?

let g:ale_python_pyls_config = {
\   'pyflakes': {
\       'enabled': 0
\   },
\   'pydocstyle': {
\       'enabled': 0
\   },
\   'mypy': {
\       'enabled': 0
\   }
\}

[eugene-bright]

As I understand the work is not done yet and the value is not passed to ale#linter#Define.
Direct call to DidChangeConfiguration doesn't make an effect either.

:let a = ale#lsp#message#DidChangeConfiguration(bufnr('%'), g:ale_python_pyls_config)

Maybe 0 value is not equivalent to JSON's false.
Also I struggle to debug pyls without running it with options -vv --log-file ~/pyls.log. Could you hint me what to do?

[eugene-bright]

As I now see ale#lsp#message#DidChangeConfiguration function is only do value wrapping.
The yielded value is consumed by ale#lsp#Send while ale#lsp_linter#StartLSP is executing.
To make all this work the dictionary must be passed as argument lsp_config to function ale#linter#Define.

I've passed a value manually to check my hypothesis.

diff --git a/ale_linters/python/pyls.vim b/ale_linters/python/pyls.vim
index eceb63f6..7b00cc1f 100644
--- a/ale_linters/python/pyls.vim
+++ b/ale_linters/python/pyls.vim
@@ -44,4 +44,5 @@ call ale#linter#Define('python', {
 \   'command_callback': 'ale_linters#python#pyls#GetCommand',
 \   'project_root_callback': 'ale#python#FindProjectRoot',
 \   'completion_filter': 'ale#completion#python#CompletionItemFilter',
+\   'lsp_config': {'pyls': {'plugins': {'pycodestyle': {'enabled': 0}}}},
 \})

I've prepared a patch #2088 to pass more args to pyls. Now debug logging can be forced by a few strings in init.vim:

let g:ale_python_pyls_extra_args = [
\   '-vv',
\   '--log-file', expand('~/pyls.log')
\]

Now I can see that settings are passed correctly

2018-11-18 23:46:40,924 UTC - DEBUG - jsonrpc.endpoint - Handling request from client {'method': 'workspace/didChangeConfiguration', 'jsonrpc': '2.0', 'id': 2, 'params': {'settings': {'pyls': {'plugins': {'pycodestyle': {'enabled': 0}}}}}}
2018-11-18 23:46:40,924 UTC - INFO - pyls.config.config - Updated settings to {'plugins': {'pycodestyle': {'enabled': 0}}}

The main problem I have at this point is passing boolean values. How can we manage this?

[w0rp]

Or you can read the documentation for ale#linter#Define. https://github.com/w0rp/ale/blob/master/doc/ale.txt#L2843

Someone can add 'lsp_config_callback': ale#VarFunc('python_plys_config') in a pull request.

[eugene-bright]

@w0rp thanks for guiding!
Is there some special Dictionary that can represent booleans?

[w0rp]

For Boolean values in a Dictionary, you should use v:true or v:false, like {'enableWhatever': v:true}. See :help v:true.