e2xgrader-core 0.1.0a1

A JupyterLab extension providing core functionality for e2xgrader

e2xgrader_core

A JupyterLab extension providing core functionality for e2xgrader

This extension is composed of a Python package named e2xgrader_core for the server extension and a NPM package named @e2xgrader/core for the frontend extension.

Requirements

• JupyterLab >= 4.0.0

Install

To install the extension, execute:

pip install e2xgrader_core

Uninstall

To remove the extension, execute:

pip uninstall e2xgrader_core

📦 Cell Filter Plugins

The E2xGraderExporter supports a plugin system for cell filters using Python entry points.
This allows you to register custom filters for specific cell types, which will be automatically discovered and applied during export.

How It Works

• The exporter looks for entry points in the group e2xgrader.cell.filters.
• Each entry point should provide a tuple: (cell_type, filter_function).
• All filters registered for a cell type are applied (in registration order) to the cell’s source during export.

Registering a Custom Cell Filter

1. Define your filter function in your package:

   def my_custom_filter(context, source):
       # Modify and return the cell source as needed
       return source.upper()
   

2. Register the filter in your pyproject.toml:

   setup.cfg:

   [project.entry-points."e2xgrader.cell.filters"]
   mycelltype = mypackage.filters:my_entry_point
   

   mypackage/filters.py:

   def my_entry_point():
       from .myfilters import my_custom_filter
       return "mycelltype", my_custom_filter
   

3. Install your package so the entry point is discoverable.

Example

Suppose you want to uppercase all sources of cells with type uppercase:

mypackage/filters.py:

def uppercase_filter(context, source):
    return source.upper()

def my_entry_point():
    return "uppercase", uppercase_filter

pyporject.toml:

[project.entry-points."e2xgrader.cell.filters"]
uppercase = mypackage.filters:my_entry_point

---

When you run the exporter, it will automatically discover and apply your filter to all cells of type uppercase.

🧩 Custom Cell Preprocessor Plugins

e2xgrader supports a plugin system for cell preprocessors using Python entry points.
This allows you to register custom preprocessors for specific cell types, which will be automatically discovered and applied during notebook processing.

How It Works

• The system looks for entry points in the group e2xgrader.cell.preprocessors.
• Each entry point should provide a tuple: (cell_type, cell_preprocessor).
• If a cell matches the cell_type, and the preprocessor object has a method matching the current preprocessor’s snake_case name, that method will be called instead of the default.

Registering a Custom Cell Preprocessor

1. Define your preprocessor class or object with a method named after the nbgrader preprocessor (in snake_case):

   # mypackage/my_preprocessors.py
   class MyCellPreprocessor:
       def clear_output(self, self_preprocessor, cell, resources, cell_index):
           # Custom logic here
           cell['outputs'] = []
           return cell, resources
   

2. Register the preprocessor in your pyproject.toml:

   The entry point be a tuple: ("mycelltype", MyCellPreprocessor)

   mypackage/my_preprocessors.py:

   class MyCellPreprocessor:
       def clear_output(self, self_preprocessor, cell, resources, cell_index):
           # Custom logic
           return cell, resources
   
   my_entry_point = ("mycelltype", MyCellPreprocessor)
   

   And in pyproject.toml:

   [project.entry-points."e2xgrader.cell.preprocessors"]
   e2xgrader.cell.preprocessors =
       mycelltype = mypackage.my_preprocessors:my_entry_point
   

3. Install your package so the entry point is discoverable.

Example

Suppose you want to clear outputs only for cells of type special:

mypackage/my_preprocessors.py:

class SpecialCellPreprocessor:
    def clear_output(self, self_preprocessor, cell, resources, cell_index):
        cell['outputs'] = []
        return cell, resources

special_entry_point = ("special", SpecialCellPreprocessor())

pyproject.toml:

[project.entry-points."e2xgrader.cell.preprocessors"]
special = mypackage.my_preprocessors:special_entry_point

---

When you run e2xgrader, it will automatically discover and apply your custom preprocessor for all cells of type special during the ClearOutput step.

---

See the source code in preprocess_cell.py and init.py for details.

Troubleshoot

If you are seeing the frontend extension, but it is not working, check that the server extension is enabled:

jupyter server extension list

If the server extension is installed and enabled, but you are not seeing the frontend extension, check the frontend extension is installed:

jupyter labextension list

Contributing

Development install

Note: You will need NodeJS to build the extension package.

The jlpm command is JupyterLab's pinned version of yarn that is installed with JupyterLab. You may use yarn or npm in lieu of jlpm below.

# Clone the repo to your local environment
# Change directory to the e2xgrader_core directory
# Install package in development mode
pip install -e ".[test]"
# Link your development version of the extension with JupyterLab
jupyter labextension develop . --overwrite
# Server extension must be manually installed in develop mode
jupyter server extension enable e2xgrader_core
# Rebuild extension Typescript source after making changes
jlpm build

You can watch the source directory and run JupyterLab at the same time in different terminals to watch for changes in the extension's source and automatically rebuild the extension.

# Watch the source directory in one terminal, automatically rebuilding when needed
jlpm watch
# Run JupyterLab in another terminal
jupyter lab

With the watch command running, every saved change will immediately be built locally and available in your running JupyterLab. Refresh JupyterLab to load the change in your browser (you may need to wait several seconds for the extension to be rebuilt).

By default, the jlpm build command generates the source maps for this extension to make it easier to debug using the browser dev tools. To also generate source maps for the JupyterLab core extensions, you can run the following command:

jupyter lab build --minimize=False

Development uninstall

# Server extension must be manually disabled in develop mode
jupyter server extension disable e2xgrader_core
pip uninstall e2xgrader_core

In development mode, you will also need to remove the symlink created by jupyter labextension develop command. To find its location, you can run jupyter labextension list to figure out where the labextensions folder is located. Then you can remove the symlink named @e2xgrader/core within that folder.

Testing the extension

Server tests

This extension is using Pytest for Python code testing.

Install test dependencies (needed only once):

pip install -e ".[test]"
# Each time you install the Python package, you need to restore the front-end extension link
jupyter labextension develop . --overwrite

To execute them, run:

pytest -vv -r ap --cov e2xgrader_core

Frontend tests

This extension is using Jest for JavaScript code testing.

To execute them, execute:

jlpm
jlpm test

Integration tests

This extension uses Playwright for the integration tests (aka user level tests). More precisely, the JupyterLab helper Galata is used to handle testing the extension in JupyterLab.

More information are provided within the ui-tests README.

Packaging the extension

See RELEASE