Startup script repl

README.md

@@ -74,7 +74,24 @@ For details about testing and troubleshooting, see the
 [development](http://pynvim.readthedocs.io/en/latest/development.html)
 documentation.
 
-#### Usage through the python REPL
+#### Autoconnect in Python/IPython REPL
+
+You can explore and use pynvim through Python/IPython REPL. For easy connection use the
+startup script in scripts/nvim_startup.py like so:
+```bash
+$ ipython -i scripts/nvim_startup.py
+# or if you prefer the Python REPL instead of IPython
+$ python -i scripts/nvim_startup.py
+```
+
+This will leave you with an Python/IPython Session that has a variable named "nvim" which 
+represents a connection to your current NVim instance.
+If you have more than one instance running, the script will ask at startup to which
+instance it shall connect to. Afterwards see [the next section](README.md#manual-usage-through-the-python-repl)
+for examples on how to use the API.
+
+
+#### Manual usage through the python REPL
 
 A number of different transports are supported, but the simplest way to get
 started is with the python REPL. First, start Nvim with a known address (or use

scripts/nvim_startup.py

@@ -0,0 +1,62 @@
+""" 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."'))