Ruby-Nvim

Ruby support for Neovim.

Clean code, minimal dependecies, no frills, no wokeness.

I would have written a shorter letter, but I did not have the time. -- Blaise Pascal

sudo gem uninstall neovim || true
sudo gem install nvim

You may prefer to also install the dependencies. Yet, this is not neccessary, as they are small and Ruby-Nvim includes a copy of them.

sudo gem install supplement mplight

Put this into a new buffer:

Neovim.plugin do |dsl|
  dsl.command :SetLine, nargs: 1 do |client,(str)|
    client.set_current_line str
  end
  dsl.function :Sum, nargs: 2, sync: true do |client,(x,y)|
    x + y
  end
  dsl.autocmd :BufEnter, pattern: "*.rb" do |client|
    client.command "echom 'Hello, Ruby!'"
  end
end

Then run these Vim commands:

w ++p ~/.config/nvim/rplugin/ruby/demo.rb
UpdateRemotePlugins

" Check the generated manifest file
split ~/.local/share/nvim/rplugin.vim
help remote-plugin-manifest

Open a new Neovim and see what happens:

e dummy.rb
SetLine some text
echo Sum(13,7)

The :ruby... commands and the rubyeval() function behave as descibed in :h ruby.

Additionally you can directly execute the buffers contents (here, I did :set number):

 1 class C
 2   def f
 3     :F
 4   end
 5 end
 6 c = C.new
~
~
~
:1,6ruby |

The last value, if it is not nil, will be added through #inspect as a comment.

 1 class C
 2   def f
 3     :F
 4   end
 5 end
 6 c = C.new
 7 #=> #<C:0x000001b347456478>
~
~
:

The classes and variables will be preserved and are available during the next call.

 5 end
 6 c = C.new
 7 #=> #<C:0x00001fd2fd1f89d0>
 8 [ c.f, C]
~
~
~
:8ruby |

This results in:

 7 #=> #<C:0x00001fd2fd1f89d0>
 8 [ c.f, C]
 9 #=> [:F, C]
~
~
:

To inhibit the output of the last value, set the $result variable to false.

 1 $result = true
 2 puts "hi"
 3 #=> nil
~
~
:1,2ruby |

The anonymous variable _ will hold the last non-nil result.

 1 7*11*13
~
~
:%ruby |

Then this will work:

 1 7*11*13
 2 #=> 1001
 3 _ - 1
~
~
:3ruby |

Output will be added to the buffer, too.

 1 puts "ba" + "na"*2
 2 print "hell"
 3 puts "o"
~
~
:1,3ruby |

Error output will be displayed on the command line, highlighted by ErrorMsg.

 1 $stderr.puts "Oh, no!"
~
~
:%ruby |

This even applies to subprocesses. They won't mess up the RPC communication.

 1 system *%w(ls -l)
 2 system *%w(ls nonexistent)
~
~
:%ruby |

Yet, I suggest not to use fork and exec, except when you're absolutely sure what you're doing.

You may specify an output buffer by its number.

 1 a = 0
 2 begin
 3   puts a
 4   a = (a * 61 + 637) % 1000
 5 end while a.nonzero?
~
~
:%ruby @3

Use :execute if you determine the buffer number by a function.

:exe "%ruby @".bufnr("#")

If you prefer, you may return an error as a value, too.

 1 $rescue = true
 2 z = 0
 3 q = 1 / z
~
~
:set ft=ruby|1,3ruby |

Then:

 1 $rescue = true
 2 z = 0
 3 q = 1 / z
 4 #!= ZeroDivisionError
 5 #!  divided by 0
 6 puts "=begin", _.backtrace, "=end"
~
~
:5ruby |

If $result is false, $rescue will be ignored.

Even non-standard errors wil be caught.

 1 def fn ; fn ; end
 2 fn
~
~
:1,2ruby |

 1 $$
 2 #=> 49042
 3 sleep 1000
~
~
:3ruby |

Then say 'kill 49042' somewhere else.

The global variable $vim will be set to the client.

~
~
:ruby $vim.command "split"

Further, the variables $range and $lines will be set.

 1 foo
 2 bar
 3 baz
~
:%ruby puts $range, $lines

The legacy variables $curbuf and $curwin are supported.

~
~
:ruby puts $curbuf.get_name, $curwin.get_height

The $_ and $. variables contain the line itself and the line number. $_ may be changed or assigned to.

:rubydo $_.strip!                                    # unindent all
:rubydo $_.insert 0, "%4d " % $.                     # number lines
:rubydo i = i.to_i.succ ; $_ = "%4d %s" % [ i, $_]   # dto.

If $_ is nil, the line will be deleted. If it is an Enumerable, each element will be inserted as its own line. All other non-string values will be converted by #to_s.

:rubydo $_ = nil if $_ =~ /^#/       # delete comment lines
:rubydo $_ = $_.split                # put each word on its own line
:rubydo $_ = [$_]*3 if ~/knock/i     # triple lines containing /knock/
:rubydo $_ = [$_, ""]                # spread by empty lines

In addition to the :rubyfile command as documented, that command can also be used to just require a Ruby file. Put the name into angle brackets, and the file will be searched in $:. Sorry, file name completion will not work.

~
~
:rubyfile <yaml>

In this case, the global variables $range and $lines will not be set. Yet, $vim still will be available. See the Nxxd gem for a nice example.

To show a list of the API functions call something like this:

pp $vim.functions.sort
pp $vim.obj_classes.map { |c| [ c.type, ($vim.obj_functions c).sort] }.to_h
~
~
:%ruby |-

Deprecated functions will be hidden unless you set the environment variable NVIM_RUBY_STRICT=off. Old functions not starting with nvim_ will be hidden. The full list of API functions can be obtained by a call to get_api_info.

pp $vim.get_api_info
~
~
:.ruby |-

See the script examples/dump_api for a more elaborated and colorized output.

Further, a simple number/cash summing tool is included.

Apples    :     3.99
Bananas   : 5 * 0.40          # multiplication
Oranges   :     3.59 - 10%    # percentage added (here subtracted)
Kiwi      :     0,40          # comma is allowed
Coconut   :     5,-           # empty decimal places
# !dot                        # dot forced now
Tangerines:     4.44
# !comma                      # result with comma
~
~
:%ruby +

Put this into a new buffer:

require "neovim"
counter = 0
Neovim.start_remote do |dsl|
  dsl.register_handler "rb_add" do |client,n|
    counter += n
    client.command "echo 'Counter value now is: '..#{counter}..'.'"
  end
  dsl.register_handler "rb_raise" do |client|
    raise "Ouch!"
  end
end

Then enter these Vim commands:

w demo_remote.rb
let chan = jobstart(['ruby','demo_remote.rb'], { 'rpc': v:true })
call rpcrequest(chan, 'rb_add', 7)
call rpcrequest(chan, 'rb_raise')
call jobstop(chan)

If you prefer, you can also use a shebang line.

#!/usr/bin/env ruby
require "neovim"
Neovim.start_remote do |dsl|
  # ... (as above)
end

Then enter these Vim commands:

w demo_remote.rb
!chmod +x %
let chan = jobstart('./demo_remote.rb', { 'rpc': v:true })
" proceed as above

Logging is a easy as this:

export NVIM_RUBY_LOG_LEVEL=all NVIM_RUBY_LOG_FILE=ruby.log
nvim +'ruby puts "hi"*10'

If the logfile isn't an absoulte path and doesn't start with "./", it will be relative to Neovim's stdpath("log").

To show the log levels, simply run in Neovim:

ruby puts Neovim::Logging::LEVELS.keys

If you are inside a Tmux, you might prefer to trace the colored log in a split window.

tmux split-window -fhd 'echo -e "\e[33m==== $$ ==== `tty` ====\e[m" ; ln -sf `tty` /tmp/tmux-`id -u`/debug ; exec cat >/dev/null 2>&1'
export NVIM_RUBY_LOG_LEVEL=all NVIM_RUBY_LOG_FILE=/tmp/tmux-`id -u`/debug

examples/demo_attach

nvim +'ruby puts "hi"*10'

You may start an interactive session and control a running Neovim through it. Open Neovim specifying the --listen option

nvim --listen /path/to/some.sock

or ask the running Neovim for its server name.

echo v:servername

Then connect to it. This requires the Intar gem.

$ intar -r neovim/remote
main:0:001> include Neovim
=> Object
main:0:002> Remote.start_client ConnectionUnix, "/path/to/some.sock" do |c|&
main:1:001> c.command "e /etc/passwd"
main:1:002> b = c.get_current_buf
=> #<Neovim::Buffer:400 1>
main:1:003> b[1]
=> ["root:*:0:0:Charlie &:/root:/bin/sh"]
main:1:004> \q!!

Put text into an X selection or a TMux register.

rubyfile <neovim/tools/copy>
'<,'>ruby xsel $lines
'<,'>ruby xsel! $lines
'<,'>ruby tmuxbuf $lines

Maybe you like to install the Nxxd gem.

rubyfile <nxxd>
ruby r = (0...0x80).to_a.map { |c| c.chr }.join
ruby puts Nxxd::Dump.new.run r

Or even:

rubyfile <nxxd>
HexDump /etc/localtime

• (C) 2024,2025 Bertram Scharpf software@bertram-scharpf.de
• License: BSD-2-Clause+
• Repository: ruby-nvim