flut 0.0.2

Flutter, but in Python

Flut

Flutter, but in Python

Overview

Flut is a Python project that exposes Flutter to Python's ecosystem. Flut is designed to honestly expose Flutter's API as closely as possible.

True Flutter

Flutter code maps almost 1:1 from Dart to Python.

// Flutter (Dart)
Container(
  padding: EdgeInsets.all(16),
  decoration: BoxDecoration(
    color: Colors.blue,
    borderRadius: BorderRadius.circular(8),
  ),
  child: Text('Hello'),
)

# Flut (Python)
Container(
  padding=EdgeInsets.all(16),
  decoration=BoxDecoration(
    color=Colors.blue,
    borderRadius=BorderRadius.circular(8),
  ),
  child=Text('Hello'),
)

Under the hood, the real Flutter widget system is used.

State-of-the-Art asyncio Integration

Flut provides a true async integration, bridging asyncio with the Flutter UI thread in a design that exactly matches Flutter. Thread safety and event loop conflicts are handled internally.

No Performance Surprises

The majority of projects using Flut will enjoy near identical performance to Flutter. FFI between Python and Dart does bring additional communication overhead, but the cost is fixed.

Status

This project is in Technical Preview.

• APIs are subject to change.
• Not ready for production use.

Installation

pip install flut

Prebuilt wheels are available for Windows (x64), macOS (x64, arm64), and Linux (x64).

Building from source is also supported and requires the Flutter SDK.

Usage

Create a file app.py:

from flut import run_app
from flut.flutter.widgets import StatelessWidget, StatefulWidget, State, Text, Center, Column, Icon, MainAxisAlignment
from flut.flutter.material import MaterialApp, Scaffold, AppBar, FloatingActionButton, Icons, ThemeData, ColorScheme, Colors, Theme


class MyApp(StatelessWidget):
    def build(self, context):
        return MaterialApp(
            title="Flut Demo",
            theme=ThemeData(
                colorScheme=ColorScheme.fromSeed(seedColor=Colors.deepPurple),
            ),
            home=MyHomePage(title="Flut Demo Home Page"),
        )


class MyHomePage(StatefulWidget):
    def __init__(self, title):
        super().__init__()
        self.title = title

    def createState(self):
        return _MyHomePageState()


class _MyHomePageState(State[MyHomePage]):
    def initState(self):
        self._counter = 0

    def _incrementCounter(self):
        def _update():
            self._counter += 1

        self.setState(_update)

    def build(self, context):
        return Scaffold(
            appBar=AppBar(
                title=Text(self.widget.title),
                backgroundColor=Theme.of(context).colorScheme.inversePrimary,
            ),
            body=Center(
                child=Column(
                    mainAxisAlignment=MainAxisAlignment.center,
                    children=[
                        Text("You have pushed the button this many times:"),
                        Text(
                            f"{self._counter}",
                            style=Theme.of(context).textTheme.headlineMedium,
                        ),
                    ],
                ),
            ),
            floatingActionButton=FloatingActionButton(
                onPressed=self._incrementCounter,
                tooltip="Increment",
                child=Icon(Icons.add),
            ),
        )


if __name__ == "__main__":
    run_app(MyApp())

Run it:

python app.py

For async support:

import asyncio
from flut import run_app_async

# ... your app code ...

if __name__ == "__main__":
    asyncio.run(run_app_async(MyApp()))

Flutter Parity

Flut is a project that brings Flutter to Python. Some features are not applicable in this context: whether due to platform limitations, overlap with Python's own ecosystem, being tied to the Dart development workflow, or simply due to its challanging nature. The following are out of scope, listed from lowest to highest priority for future consideration:

• Web Support
• Mobile Support
• Plugins
• Flutter DevTools
• Hot Reload
• Isolates
• Platform Channels
• Streams/StreamBuilder
• Non-State Mixins

The following are implemented with compromises:

• InheritedWidget Uses visitAncestorElements + dependOnInheritedElement instead of type-based lookup, resulting in O(depth) lookup vs Flutter's O(1). Negligible for typical widget trees.
• Shortcuts / Actions O(depth) action lookup vs Flutter's O(1). Negligible for typical widget trees.
• showDialog wraps the builder in a StatelessWidget proxy so the dialog's widget tree is built through the standard Dart-initiated build path, enabling callbacks in dialog children to work correctly.

Build

cd flut/.flutter
flutter build windows/macos/linux --no-tree-shake-icons

License

MIT

Disclaimer

Flut is an independent project and is not endorsed by, sponsored by, or affiliated with Google LLC. Flutter is a trademark of Google LLC.