fix: use comm package in backwards compatible way (ipython#1028)

* fix: use comm package in backwards compatible way

* feat: do not use the LoggingConfigurable class in create_comm

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* lint

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Steven Silvester <steven.silvester@ieee.org>

ipykernel/comm/__init__.py

@@ -1,5 +1,4 @@
 __all__ = ["Comm", "CommManager"]
 
-from comm.base_comm import CommManager  # noqa
-
 from .comm import Comm  # noqa
+from .manager import CommManager

ipykernel/comm/comm.py

@@ -3,19 +3,18 @@
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
-from comm.base_comm import BaseComm
+from typing import Optional
+
+import comm.base_comm
+import traitlets.config
 
 from ipykernel.jsonutil import json_clean
 from ipykernel.kernelbase import Kernel
 
 
-class Comm(BaseComm):
-    """Class for communicating between a Frontend and a Kernel"""
-
-    def __init__(self, *args, **kwargs):
-        self.kernel = None
-
-        super().__init__(*args, **kwargs)
+# this is the class that will be created if we do comm.create_comm
+class BaseComm(comm.base_comm.BaseComm):
+    kernel: Optional[Kernel]
 
     def publish_msg(self, msg_type, data=None, metadata=None, buffers=None, **keys):
         """Helper for sending a comm message on IOPub"""
@@ -40,4 +39,15 @@ def publish_msg(self, msg_type, data=None, metadata=None, buffers=None, **keys):
         )
 
 
+# but for backwards compatibility, we need to inherit from LoggingConfigurable
+class Comm(traitlets.config.LoggingConfigurable, BaseComm):
+    """Class for communicating between a Frontend and a Kernel"""
+
+    def __init__(self, *args, **kwargs):
+        self.kernel = None
+        # Comm takes positional arguments, LoggingConfigurable does not, so we explicitly forward arguments
+        traitlets.config.LoggingConfigurable.__init__(self, **kwargs)
+        BaseComm.__init__(self, *args, **kwargs)
+
+
 __all__ = ["Comm"]

ipykernel/comm/manager.py

@@ -3,4 +3,13 @@
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
-from comm.base_comm import CommManager  # noqa
+
+import comm.base_comm
+import traitlets.config
+
+
+class CommManager(traitlets.config.LoggingConfigurable, comm.base_comm.CommManager):
+    def __init__(self, **kwargs):
+        # CommManager doesn't take arguments, so we explicitly forward arguments
+        traitlets.config.LoggingConfigurable.__init__(self, **kwargs)
+        comm.base_comm.CommManager.__init__(self)

ipykernel/ipkernel.py

@@ -15,7 +15,7 @@
 from traitlets import Any, Bool, Instance, List, Type, observe, observe_compat
 from zmq.eventloop.zmqstream import ZMQStream
 
-from .comm import Comm
+from .comm.comm import BaseComm
 from .compiler import XCachingCompiler
 from .debugger import Debugger, _is_debugpy_available
 from .eventloops import _use_appnope
@@ -42,7 +42,7 @@
 
 def create_comm(*args, **kwargs):
     """Create a new Comm."""
-    return Comm(*args, **kwargs)
+    return BaseComm(*args, **kwargs)
 
 
 comm.create_comm = create_comm