nvim_startup.py

""" Startup script for IPython an Python REPL that will connect to a running 
NeoVim instance automatically or ask the user which NeoVim instance to connect 
to. After connection there is a variable called "nvim" that gives acccess to 
the endpoint.
"""
import atexit
from glob import glob
import pynvim


class NvimAutoAttachException(Exception):
    '''Exception class that will be raised by this script'''


def __let_user_choose_instance(nvim_instances):
    for idx, inst in enumerate(nvim_instances):
        with pynvim.attach('socket', path=inst) as nvim_endpoint:
            nvim_endpoint.command(
                'echon "I am Instance Nr {}: " $NVIM_LISTEN_ADDRESS'.format(
                    idx
                )
            )

    for idx, inst in enumerate(nvim_instances):
        print('Instance Nr {}: {}'.format(idx, inst))

    while True:
        try:
            print(
                'Which Nvim instance should I connect to? '
                '(Look at the bottom of the vim instance you want to connect '
                'to)'
            )
            inst_nr = int(input('Connect to Instance Nr: '))
            chosen_inst = nvim_instances[inst_nr]
            break
        except (ValueError, IndexError):
            continue

    return chosen_inst


def autoattach_to_nvim(glob_expr='/tmp/nvim*/0'):
    '''Returns a nvim endpoint if there is only one instance.
    If there are more instances, asks the user which one to pick.
    Raises NvimAutoAttachException if there are no NVim instances.
    '''
    nvim_instances = glob(glob_expr)
    if not nvim_instances:
        raise NvimAutoAttachException(
            'Could not find any running NVim instances.'
        )
    if len(nvim_instances) > 1:
        chosen_inst = __let_user_choose_instance(nvim_instances)
    else:
        chosen_inst = nvim_instances[0]
    return pynvim.attach('socket', path=chosen_inst)


nvim = autoattach_to_nvim()
nvim.command('echo "Connected to Python REPL."')
atexit.register(lambda: nvim.command('echo "Python REPL disconnected."'))