I want a simple command that changes the range that the user selected to a constant string I set (with possibly differently number of lines) - effectively adding lines if the constant string has more. The following code does nothing but randomly inserts newline. What went wrong?

class Plugin(object):
    def __init__(self, nvim):
        self.nvim = nvim

    @neovim.command("MyCommand", range="", nargs="*", sync=True)
    def my_command(self, args, range):
        start_line, end_line = range
        region = self.nvim.current.buffer.range(start_line-1, end_line)
        aa="string \r ssss"  
        if len(aa)>0:
            region[:] = '\r'.split(aa)

  • 1
    I'm not sure to understand what you want to achieve. Maybe is you would give an example: current buffer content, command call with all its arguments and expected result it would help. Commented Apr 21, 2023 at 4:21
  • I think i confused you with the word buffer. I want the equivalent of 'csomestring\n' from visual. and perhaps it can work as well by commands (when doing :MyCommand after selecting ramge)
    – eyal karni
    Commented Apr 21, 2023 at 12:37

1 Answer 1


I would add a file: nvim\rplugin\python3\mycommand.py to the nvim configuration.

With the following content:

import pynvim

class Plugin(object):
    def __init__(self, nvim):
        self.nvim = nvim

    @pynvim.command("MyCommand", range="", nargs=0, sync=True)
    def my_command(self, args, rgn):
        start_line, end_line = rgn
        self.nvim.command(f"echo {start_line} {end_line}")

        lines = text.split("\r")

        if len(lines) < end_line + 1 - start_line:
            # Remove lines in excess:
            self.nvim.call("deletebufline", "%", start_line + len(lines), end_line)

        for i in range(len(lines) - (end_line + 1 - start_line)):
            # Insert missing blank lines:
            self.nvim.call("appendbufline", "%", end_line, "")

        for index, line in enumerate(lines):
            # Replace lines with the text:
            self.nvim.call("setbufline", "%", start_line + index, line)

It assumes that pynvim package is available in the Python version that Neovim is using (defined in g:python3_host_prog)

  • @eyal, Did you had the chance to test the solution? Is it working for you? Commented Apr 27, 2023 at 14:30
  • 1
    No, will check it tomorrow. Looks good. I thought a 5 line solution should be possible. Maybe not.
    – eyal karni
    Commented Apr 27, 2023 at 23:25
  • 1
    Works really good. Thanks. I had to change nargs to "*" . The code will be in repo under MIT license , if you dont mind
    – eyal karni
    Commented Apr 28, 2023 at 13:10
  • Thanks for your feedback :-) no problem for the MIT license ;-) Commented Apr 28, 2023 at 13:31
  • 1

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