Shim to support the notebook extensions

nbclassic/__init__.py

@@ -1,13 +1,50 @@
 import os
+import sys
 from ._version import __version__ 
 
+
 # Packagers: modify this line if you store the notebook static files elsewhere
 DEFAULT_STATIC_FILES_PATH = os.path.join(os.path.dirname(__file__), "static")
 
-# Packagers: modify the next line if you store the notebook template files
-# elsewhere
 
-# Include both notebook/ and notebook/templates/.  This makes it
+# Notebook shim to ensure notebook extensions backwards compatiblity.
+
+try:
+    from notebook._version import __version__ as notebook_version
+except Exception as e:
+    # Notebook is not available on the platform.
+    # We shim the complete notebook module.
+    print('No notebook python package found. Shimming notebook to jupyter_server for notebook extensions backwards compatiblity.')
+    import jupyter_server
+    sys.modules["notebook"] = jupyter_server
+    from jupyter_server.base import handlers
+    from notebook.base import handlers as notebook_handlers
+    handlers.IPythonHandler = handlers.JupyterHandler
+    notebook_handlers.IPythonHandler = handlers.JupyterHandler
+
+if "notebook_version" in locals():
+    # Notebook is available on the platform.
+    # We shim based on the notebook version.
+    if notebook_version < "7":
+        from .shim_notebook import shim_notebook_6
+        print('Shimming existing notebook python package < 7 to jupyter_server for notebook extensions backwards compatiblity.')
+        shim_notebook_6()
+    else:
+        from .shim_notebook import shim_notebook_7_and_above
+        print('Shimming existing notebook python package >= 7 to jupyter_server for notebook extensions backwards compatiblity.')
+        shim_notebook_7_and_above()
+
+
+# Sanity check for the notebook shim.
+
+from jupyter_server.base.handlers import IPythonHandler as JupyterServerIPythonHandler
+assert JupyterServerIPythonHandler.__name__ == "JupyterHandler"
+
+from notebook.base.handlers import IPythonHandler as NotebookIPythonHandler
+assert NotebookIPythonHandler.__name__ == "JupyterHandler"
+
+
+# Include both nbclassic/ and nbclassic/templates/.  This makes it
 # possible for users to override a template with a file that inherits from that
 # template.
 #

nbclassic/shim_notebook.py

@@ -0,0 +1,96 @@
+"""Shim the notebook module for the classic extensions.
+"""
+
+# Copyright (c) Jupyter Development Team.
+# Distributed under the terms of the Modified BSD License.
+
+import sys
+
+
+def shim_notebook_6():
+    """Define in sys.module the needed notebook packages that should be fullfilled by
+    their corresponding and backwards-compatible jupyter-server packages.
+
+    TODO Can we lazy load these loadings?
+
+    Note: We could a custom module loader to achieve similar functionality. The 
+    logic thar conditional loading seems to be more complicated than simply
+    listing by hand the needed subpackages but could avoid latency on server start.
+
+    https://docs.python.org/3/library/importlib.html#importlib.abc.Loader
+
+    These are the notebook packages we need to shim:
+
+    auth
+    base
+    bundler <- no, already available in nbclassic
+    edit <- no, already available in nbclassic
+    files
+    gateway
+    i18n <- no, already available in nbclassic
+    kernelspecs
+    nbconvert
+    notebook <- no, already available in nbclassic
+    prometheus
+    services
+    static <- no, already available in nbclassic
+    templates <- no, already available in nbclassic
+    terminal <- no, already available in nbclassic
+    tests <- no, already available in nbclassic
+    tree <- no, already available in nbclassic
+    view
+    __init__.py <- no, already available in nbclassic
+    __main__.py <- no, already available in nbclassic
+    _sysinfo.py <- no, already available in nbclassic
+    _tz.py
+    _version.py <- no, already available in nbclassic
+    config_manager.py <- no, already available in nbclassic
+    extensions.py <- no, already available in nbclassic
+    jstest.py <- no, already available in nbclassic
+    log.py
+    nbextensions.py <- no, already available in nbclassic
+    notebookapp.py <- no, already available in nbclassic
+    serverextensions.py <- no, already available in nbclassic
+    traittypes.py <- no, already available in nbclassic
+    transutils.py <- no, already available in nbclassic
+    utils.py
+
+    """
+
+    from jupyter_server import auth
+    sys.modules["notebook.auth"] = auth
+    from jupyter_server import base
+    sys.modules["notebook.base"] = base
+    from jupyter_server import files
+    sys.modules["notebook.files"] = files
+    from jupyter_server import gateway
+    sys.modules["notebook.gateway"] = gateway
+    from jupyter_server import kernelspecs
+    sys.modules["notebook.kernelspecs"] = kernelspecs
+    from jupyter_server import nbconvert
+    sys.modules["notebook.nbconvert"] = nbconvert
+    from jupyter_server import prometheus
+    sys.modules["notebook.prometheus"] = prometheus
+    from jupyter_server import services
+    sys.modules["notebook.services"] = services
+    from jupyter_server import view
+    sys.modules["notebook.view"] = view
+    from jupyter_server import _tz
+    sys.modules["notebook._tz"] = _tz
+    from jupyter_server import log
+    sys.modules["notebook.log"] = log
+    from jupyter_server import utils
+    sys.modules["notebook.utils"] = utils
+
+    base.handlers.IPythonHandler = base.handlers.JupyterHandler
+    sys.modules["notebook.base.handlers.IPythonHandler"] = base.handlers.JupyterHandler
+
+
+def shim_notebook_7_and_above():
+    """For now, notebook v7 should be shimmed for now the same way 
+    as notebook v6. This distinction could be useful for later 
+    notebook >=7 evolutions.
+
+    TODO Discuss and remove if not needed.
+    """
+    shim_notebook_6()