Replace ipykernel dependency by the comm dependency

python/ipywidgets/ipywidgets/__init__.py

@@ -21,17 +21,21 @@
 from ._version import __version__, __protocol_version__, __jupyter_widgets_controls_version__, __jupyter_widgets_base_version__
 
 import os
+import sys
 
 from traitlets import link, dlink
 from IPython import get_ipython
-try:
-    from comm import get_comm_manager
-except ImportError:
+
+# Using the comm implementation through ipykernel if available
+if "ipykernel" in sys.modules:
     def get_comm_manager():
         ip = get_ipython()
 
         if ip is not None and getattr(ip, "kernel", None) is not None:
             return get_ipython().kernel.comm_manager
+# Using the comm package
+else:
+    from comm import get_comm_manager
 
 from .widgets import *
 

python/ipywidgets/ipywidgets/widgets/widget.py

@@ -6,6 +6,7 @@
 in the Jupyter notebook front-end.
 """
 import os
+import sys
 import typing
 from contextlib import contextmanager
 from collections.abc import Iterable
@@ -524,13 +525,13 @@ def open(self):
             if self._model_id is not None:
                 args['comm_id'] = self._model_id
 
-            try:
-                from comm import create_comm
-            except ImportError:
+            if "ipykernel" in sys.modules:
                 def create_comm(**kwargs):
                     from ipykernel.comm import Comm
 
                     return Comm(**kwargs)
+            else:
+                from comm import create_comm
 
             self.comm = create_comm(**args)
 

python/ipywidgets/setup.cfg

@@ -34,7 +34,7 @@ zip_safe = False
 packages = find:
 
 install_requires =
-  ipykernel>=4.5.1
+  comm>=0.1.3
   ipython>=6.1.0
   traitlets>=4.3.1
   widgetsnbextension~=4.0.7