Backport PR jupyter-widgets#3811: Replace ipykernel dependency by the…

… comm dependency

dev-install.sh

@@ -41,11 +41,11 @@ echo -n "widgetsnbextension"
 cd widgetsnbextension
 pip install -v -e .
 if [[ "$OSTYPE" == "msys" ]]; then
-    jupyter nbextension install --overwrite --py $nbExtFlags widgetsnbextension
+    jupyter nbextension install --overwrite --py $nbExtFlags widgetsnbextension || true
 else
-    jupyter nbextension install --overwrite --py --symlink $nbExtFlags widgetsnbextension
+    jupyter nbextension install --overwrite --py --symlink $nbExtFlags widgetsnbextension || true
 fi
-jupyter nbextension enable --py $nbExtFlags widgetsnbextension
+jupyter nbextension enable --py $nbExtFlags widgetsnbextension || true
 cd ..
 
 if test "$skip_jupyter_lab" != yes; then

ipywidgets/__init__.py

@@ -19,18 +19,11 @@
 """
 
 import os
+import sys
 
 from traitlets import link, dlink
 from IPython import get_ipython
 
-try:
-    from comm import get_comm_manager
-except ImportError:
-    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
 
 from ._version import version_info, __version__, __protocol_version__, __jupyter_widgets_controls_version__, __jupyter_widgets_base_version__
 from .widgets import *
@@ -46,7 +39,8 @@ 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)

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)

ipywidgets/tests/test_embed.py

@@ -7,9 +7,6 @@
 
 import traitlets
 
-# This has a byproduct of setting up the comms
-import ipykernel.ipkernel
-
 from ..widgets import IntSlider, IntText, Text, Widget, jslink, HBox, widget_serialization, widget
 from ..embed import embed_data, embed_snippet, embed_minimal_html, dependency_state
 

ipywidgets/widgets/widget.py

@@ -23,6 +23,7 @@
 from ipython_genutils.py3compat import string_types, PY3
 from IPython.display import display
 from json import loads as jsonloads, dumps as jsondumps
+from .. import comm
 
 from base64 import standard_b64encode
 
@@ -500,15 +501,7 @@ def open(self):
             if self._model_id is not None:
                 args['comm_id'] = self._model_id
 
-            try:
-                from comm import create_comm
-            except ImportError:
-                def create_comm(**kwargs):
-                    from ipykernel.comm import Comm
-
-                    return Comm(**kwargs)
-
-            self.comm = create_comm(**args)
+            self.comm = comm.create_comm(**args)
 
     @observe('comm')
     def _comm_changed(self, change):

setup.py

@@ -109,7 +109,7 @@
 
 setuptools_args = {}
 install_requires = setuptools_args['install_requires'] = [
-    'ipykernel>=4.5.1',
+    'comm>=0.1.3',
     'ipython_genutils~=0.2.0',
     'traitlets>=4.3.1',
     # TODO: Dynamically add this dependency