Jupyter / IPython notebook loader for Python >= 3.4 (PEP 451)

nbloader.py

#http://jupyter-notebook.readthedocs.io/en/stable/examples/Notebook/Importing%20Notebooks.html

import io, os, sys, types
from typing import override

import importlib, importlib.abc, importlib.util

from IPython import get_ipython
from nbformat import read
from IPython.core.interactiveshell import InteractiveShell


def find_notebook(fullname, path=None):
    """find a notebook, given its fully qualified name and an optional path

    This turns "foo.bar" into "foo/bar.ipynb"
    and tries turning "Foo_Bar" into "Foo Bar" if Foo_Bar
    does not exist.
    """
    name = fullname.rsplit('.', 1)[-1]
    if not path:
        path = ['']
    for d in path:
        nb_path = os.path.join(d, name + ".ipynb")
        if os.path.isfile(nb_path):
            return nb_path
        # let import Notebook_Name find "Notebook Name.ipynb"
        nb_path = nb_path.replace("_", " ")
        if os.path.isfile(nb_path):
            return nb_path

#
class NotebookLoader(importlib.abc.Loader):
    """Module Loader for Jupyter Notebooks"""
    def __init__(self, fullname, path=None):
        self.shell = InteractiveShell.instance()
        self.fullname = fullname
        self.path = path

    def create_module(self, spec):
        
        mod = types.ModuleType(spec.name)
        mod.__file__ = spec.loader.path
        mod.__loader__ = self
        mod.__dict__['get_ipython'] = get_ipython

        return mod

    def exec_module(self, module):
        """import a notebook as a module"""
        path = find_notebook(self.fullname, self.path)

        print ("importing Jupyter notebook from %s" % path)

        # load the notebook object
        with io.open(path, 'r', encoding='utf-8') as f:
            nb = read(f, 4)
        
        # extra work to ensure that magics that would affect the user_ns
        # actually affect the notebook module's ns
        save_user_ns = self.shell.user_ns
        self.shell.user_ns = module.__dict__

        try:
          for cell in nb.cells:
            if cell.cell_type == 'code':
                # transform the input to executable Python
                code = self.shell.input_transformer_manager.transform_cell(cell.source)
                # run the code in themodule
                exec(code, module.__dict__)
        finally:
            self.shell.user_ns = save_user_ns
        
#
class NotebookFinder(importlib.abc.MetaPathFinder):
    """Module finder that locates Jupyter Notebooks"""
    def __init__(self):
        self.loaders = {}

    def find_spec(self, fullname, path=None, target=None):
        nb_path = find_notebook(fullname, path)
        if not nb_path:
            return None

        key = path
        if path:
            # lists aren't hashable
            key = os.path.sep.join(path)
        else:
            key = fullname

        if key not in self.loaders:
            self.loaders[key] = importlib.util.spec_from_loader(fullname, NotebookLoader(fullname, path))
        return self.loaders[key]

#
#happens when this is imported
#Still not a proper jupyter extension though
sys.meta_path.append(NotebookFinder())

The code that creates the key is not completely trustworthy yet.

Eventually it needs to be submit back to the Jupyter project.

The code at https://jupyter-notebook.readthedocs.io/en/stable/examples/Notebook/Importing%20Notebooks.html no longer works.