Radiant: A single-file Python runtime bridge (CPython ↔ Brython)

A lightweight and Python-first runtime bridge for building web applications with Brython.

Overview

Radiant is a framework that bridges Python on the server (CPython) with Python in the browser (Brython). It allows developers to write web applications entirely in Python, without needing to write JavaScript code.

Features

• Write both frontend and backend code in Python
• Simple API for DOM manipulation
• Built-in HTTP server for development
• Support for RESTful API endpoints (GET, POST)
• View routing for multi-page applications
• JSON response helpers
• IPv4 and IPv6 support

Installation

pip install radiant-runtime-bridge

Quick Start

Minimal Example

Create a simple web application with just a few lines of code:

# Base class that binds the Python server with the Brython frontend
from radiant import BrythonServer


class App(BrythonServer):
    # Application entry point.
    # Inherits the Radiant runtime that exposes HTML primitives and the browser document.

    def __init__(self):
        self.document <= self.html.H1("Radiant · Python Runtime Bridge")
        self.document <= self.html.P(
            "This application connects a Python backend with a Brython-powered frontend "
            "through a unified runtime."
        )


if __name__ == "__main__":
    # Start the embedded HTTP server with default address and port
    App.serve()

    # Alternative explicit binding
    # App.serve(ip="127.0.0.1", port=8080)

Run the application:

python main.py

Then open your browser to http://localhost:5050 (default port).

API Examples

Creating API Endpoints

from radiant import BrythonServer, json_response


class App(BrythonServer):

    @BrythonServer.get("/api/get")
    def get_api(**kwargs):
        """Python rendered function"""
        data = {
            "on_get": "ok",
            **kwargs,
        }
        return json_response(data)

    @BrythonServer.post("/api/post")
    def post_api(**kwargs):
        """Python rendered function"""
        data = {
            "on_post": "ok",
            **kwargs,
        }
        return json_response(data)


if __name__ == "__main__":
    App.serve()

Creating Multiple Views

# Core Radiant runtime and optional JSON utilities
from radiant import BrythonServer, json_response


class App(BrythonServer):
    # Example application demonstrating classic browser navigation
    # with server-rendered views using Radiant.

    def __init__(self):
        # Executed on each page load
        print("Application request received")

        # Main page content
        self.document <= self.html.H1("Radiant · Server-Rendered Views")
        self.document <= self.html.P(
            "This example demonstrates browser-controlled navigation "
            "with full page reloads, where each route renders a new view "
            "handled by the Radiant server."
        )

        # Navigation links triggering full page reloads
        self.document <= self.html.A("Open View 1", href="/page1")
        self.document <= self.html.BR()
        self.document <= self.html.A("Open View 2", href="/page2")
        self.document <= self.html.BR()
        self.document <= self.html.A("Open View 3", href="/page3")

    @BrythonServer.view("/page1")
    def page1(self):
        # View rendered after a full page reload
        self.document <= self.html.H1("View 1")
        self.document <= self.html.P(
            "This page was rendered after a full browser reload "
            "and handled by the Radiant server."
        )
        self.document <= self.html.A("Back to Home", href="/")


if __name__ == "__main__":
    # Start the application using default server settings
    App.serve()

Brython Enhancement

select

The select method enables batch operations on multiple DOM elements. Functions can be applied to all selected elements at once:

selection = self.select('.my-class')
selection.bind('mouseover', lambda evt: print(evt))
selection.style.color = 'cyan'
selection.style = {'background-color': 'red'}

html

The html module offers a Pythonic way to create and manipulate HTML elements:

# Create elements with CSS classes
title = self.html.H1('My Title', Class='header')

# Dynamic class management
title.classes.append('active')
title.classes.extend(['large', 'visible'])

# Python-style CSS properties
title.styles.background_color = 'blue'
title.styles.font_size = '16px'

# Context-based nesting
with self.html.DIV().context as container:
    with self.html.UL().context as list:
        with self.html.LI().context:
            html.SPAN("List item")

A complete working example of context managers can be found in examples/html_context_manager/main.py.

styles

The styles object provides a cleaner syntax for managing CSS properties:

selection = self.select('.my-class')
selection.styles.background_color = 'red'
selection.styles.color = 'white'

Important Notes

• Radiant is designed for development, testing, and prototyping
• Not recommended for production use without additional security measures
• No built-in authentication or authorization

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

This project is licensed under the BSD-2-Clause License - see the LICENSE.md file for details.

Links

• GitHub Repository
• PyPI Package