Companyons

Interactively develop Java/Vaadin web components applications with embedded CPython in dynamic Notebook style.

Requirements

• Java 17+
• Gradle 7.3+
• Python 3 ( < 3.10 for now! – Will later be auto-installable via Gradle …)
• Latest Jep installed into your Python environment (Will also later be handled by Gradle …)

Getting started

Open gradle.properties and provide the full path to your preferred Python executable:

pythonExe = /path/to/your/bin/python

Or, on Windows, respectively:

pythonExe = C:\\path\\to\\your\\python.exe

Then, run the Companyons backend with:

> gradle bootRun

Which will automatically download all Java dependencies, build the project, and finally open its frontend in your default web browser.

Hello, world!

All Markdown files from your working directory are automatically loaded as companyon apps. So is this README.md loaded on startup:

• The right-side console can be resized using the draggable handle at its left border.

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All fenced code blocks of python type are loaded as executable code, and appear in editor widgets within the console – like those from this simple example:

• Import any Vaadin components via their Java package paths:

from com.vaadin.flow.component.html import H1, H2, H3
from com.vaadin.flow.component.button import Button

• Define a function that adds components to the main view area:

@UI.accessor
def append_hello_sayer():
    hello_sayer = Button('Say hello!')

    @UI.listener
    @UI.accessor
    def say_hello():
        UI.view.add(
            H2('Hello, world!'),
            H3('Now create your own companyons ...'))

    hello_sayer.addClickListener(say_hello)
    UI.view.add(H1("A simple companyon"), hello_sayer)

• Call the function:

append_hello_sayer()

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By clicking on the step-forward buttons next to the editor widgets, their code is executed in the Python sub-interpreter attached to the README app:

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Now click on the new Say hello! button and see what happens: