Replace ipykernel dependency by the comm dependency

python/ipywidgets/ipywidgets/__init__.py

@@ -26,17 +26,6 @@
 from traitlets import link, dlink
 from IPython import get_ipython
 
-# ipykernel <6.18 when the comm package did not exist
-if "ipykernel" in sys.modules and "comm" not 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 *
 
 
@@ -48,7 +37,8 @@ def load_ipython_extension(ip):
 
 def register_comm_target(kernel=None):
     """Register the jupyter.widget comm target"""
-    comm_manager = get_comm_manager()
+    from . import comm
+    comm_manager = comm.get_comm_manager()
     if comm_manager is None:
         return
     comm_manager.register_target('jupyter.widget', Widget.handle_comm_opened)

python/ipywidgets/ipywidgets/comm.py

@@ -0,0 +1,33 @@
+# compatibility shim for ipykernel < 6.18
+import sys
+from IPython import get_ipython
+import comm
+
+
+def requires_ipykernel_shim():
+    if "ipykernel" in sys.modules:
+        import ipykernel
+
+        version = ipykernel.version_info
+        return version < (6, 18)
+    else:
+        return False
+
+
+def get_comm_manager():
+    if requires_ipykernel_shim():
+        ip = get_ipython()
+
+        if ip is not None and getattr(ip, "kernel", None) is not None:
+            return get_ipython().kernel.comm_manager
+    else:
+        return comm.get_comm_manager()
+
+
+def create_comm(*args, **kwargs):
+    if requires_ipykernel_shim():
+        from ipykernel.comm import Comm
+
+        return Comm(*args, **kwargs)
+    else:
+        return comm.create_comm(*args, **kwargs)

python/ipywidgets/ipywidgets/widgets/widget.py

@@ -15,6 +15,7 @@
     Any, HasTraits, Unicode, Dict, Instance, List, Int, Set, Bytes, observe, default, Container,
     Undefined)
 from json import loads as jsonloads, dumps as jsondumps
+from .. import comm
 
 from base64 import standard_b64encode
 
@@ -525,16 +526,7 @@ def open(self):
             if self._model_id is not None:
                 args['comm_id'] = self._model_id
 
-            # ipykernel <6.18 when the comm package did not exist
-            if "ipykernel" in sys.modules and "comm" not 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)
+            self.comm = comm.create_comm(**args)
 
     @observe('comm')
     def _comm_changed(self, change):