Metadata-Version: 2.4
Name: wybthon
Version: 0.39.0
Summary: SolidJS for Python: a signals-first client-side SPA framework running on Pyodide
Author: Owen Carey
License: MIT License
        
        Copyright (c) 2026 Owen Carey
        
        Permission is hereby granted, free of charge, to any person obtaining a copy
        of this software and associated documentation files (the "Software"), to deal
        in the Software without restriction, including without limitation the rights
        to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
        copies of the Software, and to permit persons to whom the Software is
        furnished to do so, subject to the following conditions:
        
        The above copyright notice and this permission notice shall be included in all
        copies or substantial portions of the Software.
        
        THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
        IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
        FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
        AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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        OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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Project-URL: Homepage, https://github.com/wybthon/wybthon
Project-URL: Repository, https://github.com/wybthon/wybthon
Project-URL: Issues, https://github.com/wybthon/wybthon/issues
Project-URL: Changelog, https://github.com/wybthon/wybthon/blob/main/CHANGELOG.md
Classifier: Development Status :: 2 - Pre-Alpha
Classifier: Intended Audience :: Developers
Classifier: License :: OSI Approved :: MIT License
Classifier: Programming Language :: Python :: 3
Classifier: Programming Language :: Python :: 3 :: Only
Classifier: Programming Language :: Python :: 3.14
Classifier: Environment :: WebAssembly
Classifier: Framework :: AsyncIO
Classifier: Topic :: Internet :: WWW/HTTP :: Dynamic Content
Classifier: Typing :: Typed
Requires-Python: >=3.14
Description-Content-Type: text/markdown
License-File: LICENSE
Dynamic: license-file

<p align="center">
  <img src="docs/assets/banner.jpg" alt="Wybthon" width="800" />
</p>

<p align="center">
  <em>SolidJS for Python. Build interactive web apps in Python, no JavaScript required.</em>
</p>

<p align="center">
  <a href="https://github.com/wybthon/wybthon/actions/workflows/ci.yml"><img src="https://github.com/wybthon/wybthon/actions/workflows/ci.yml/badge.svg" alt="CI" /></a>
  <a href="https://github.com/wybthon/wybthon/actions/workflows/release.yml"><img src="https://github.com/wybthon/wybthon/actions/workflows/release.yml/badge.svg" alt="Release" /></a>
  <a href="https://pypi.org/project/wybthon/"><img src="https://img.shields.io/pypi/v/wybthon" alt="PyPI Version" /></a>
  <a href="https://pypi.org/project/wybthon/"><img src="https://img.shields.io/pypi/pyversions/wybthon" alt="Python Versions" /></a>
  <a href="LICENSE"><img src="https://img.shields.io/pypi/l/wybthon" alt="License: MIT" /></a>
  <a href="https://wybthon.com/"><img src="https://img.shields.io/website?url=https%3A%2F%2Fwybthon.com&label=docs" alt="Docs" /></a>
</p>

<p align="center">
  <a href="https://wybthon.com/">Documentation</a> ·
  <a href="https://wybthon.com/getting-started/">Getting Started</a> ·
  <a href="https://wybthon.com/examples/">Examples</a> ·
  <a href="CONTRIBUTING.md">Contributing</a>
</p>

---

## Overview

Wybthon brings SolidJS 2.0's reactive model to Python and runs it in the browser through [Pyodide](https://pyodide.org/). You write run-once function components with typed props and return HTML written as Python 3.14 template strings: `html(t"<p>Count: {count()}</p>")`. Like Solid's, Wybthon's compiler turns every dynamic expression in that markup into a getter, so each one updates only the text node or attribute that reads it; components never re-render. Async data, loading and error boundaries, actions with optimistic state, draft-first stores, server rendering, a router, forms, and context are all built in.

## Features

- **A compiler, as in Solid.** Wybthon's compiler rewrites `html(t"...")` calls on Python's syntax tree before a module runs. An expression that calls something, reads an attribute, or indexes (`{count() * 2}`, `{props.title}`, `{row["label"]}`) becomes a getter, and a component call in the markup receives getters for its props, so you never wrap markup in lambdas. It runs in `wyb build` and `wyb dev`, in an import hook that `import wybthon` installs, under pytest, and for scripts with `wyb run`.
- **HTML templates compiled ahead of time.** `html(t"...")` takes a [PEP 750](https://peps.python.org/pep-0750/) template string. The compiler parses and validates each literal and writes its mount code into the module, so a production build never parses a template or generates code at run time; every instance clones a native `<template>` with one command and fills its slots.
- **Run-once components with typed props.** Components declare their inputs on a `Props` class with plain annotations, and `props.title` is a tracked read of the parent's value, as in Solid. Callbacks are fields annotated as callable. Pyright, Pylance, and mypy check every component call with no plugin.
- **Components cost what their markup costs.** A constant prop subscribes to nothing, a binding that reads nothing reactive allocates no computation, and `Show`, `For`, `Repeat`, and `Switch` are native regions rather than wrapper components.
- **Signals with automatic batching.** `create_signal`, `create_memo`, and `create_effect`. Writes are staged and applied once per microtask (and at the end of every event handler), so there's no `batch()` to remember.
- **Async-first data.** An `async def` passed to `create_memo` is the data-fetching primitive. `Loading` shows a fallback until it resolves; later refetches run as **transitions** that hold the dependent UI on the old state until the new value lands, so the screen never tears. `create_deferred` is the async memo that never holds the rest of the UI, and `is_pending`, `latest`, `resolve`, and `refresh` observe or drive async state.
- **Actions and optimistic state.** `action` makes a mutation a transaction; `create_optimistic` and `create_optimistic_store` show temporary values that revert when the action settles.
- **Draft-first stores.** `create_store` setters take a function that mutates a draft with plain Python; reads are tracked per path. `reconcile`, `snapshot`, `deep`, and projections are included.
- **Flow control and boundaries.** `Show`, `For`, `Repeat`, `Switch`/`Match`, and `dynamic` update only the affected subtree; `Loading`, `Reveal`, and `Errored` swap in fallbacks without tearing down sibling trees.
- **Server rendering and hydration.** Render the same components to HTML in CPython at build time or per request, stream `Loading` boundaries as they resolve, set the response status and headers from components, and `hydrate` the result in the browser.
- **One bridge crossing per update.** A small virtual DOM batches every mutation in a flush into one call to a JavaScript kernel, which matters when every DOM call would otherwise cross from Python to JavaScript.
- **Router, forms, context, portals, and lazy loading.** `wybthon.router`, `wybthon.forms` with validators and ARIA helpers, callable `Context` objects, `Portal`, and `lazy` and `lazy_module` with explicit build chunks.
- **Testing in plain CPython.** `wybthon.testing` renders components into an in-memory DOM and queries them by text, role, label, and test id. Templates in test modules are compiled by Wybthon's pytest plugin.
- **Tooling.** `wyb init` scaffolds a project, `wyb dev` rebuilds and reloads on change, `wyb build` writes a production bundle with the manifest inlined and the runtime preloaded, and `wyb run` runs a script with its templates compiled.

## Quick start

### Installation

Wybthon requires Python 3.14.

```bash
pip install wybthon
wyb init my-app
cd my-app
wyb dev --open
```

### Usage

```python
from collections.abc import Callable

from wybthon import (
    Errored,
    For,
    Loading,
    ParentProps,
    Props,
    Show,
    action,
    component,
    create_signal,
    create_store,
    html,
    render,
)


class CounterProps(Props):
    step: int = 1
    on_change: Callable[[int], None] | None = None


@component
def Counter(props: CounterProps):
    count, set_count = create_signal(0)

    def increment():
        new_count = count() + props.step
        set_count(new_count)
        if props.on_change is not None:
            props.on_change(new_count)

    return html(t"""
      <div>
        <p>Count: {count()} (doubled: {count() * 2})</p>
        <button onclick={increment}>+</button>
        {Show(count() > 5, html(t"<p>That's a lot of clicks.</p>"))}
      </div>
    """)


class PanelProps(ParentProps):
    title: str


@component
def Panel(props: PanelProps):
    return html(t'<section class="panel"><h2>{props.title}</h2>{props.children}</section>')


@component
def Todos():
    store, set_store = create_store({"todos": []})
    draft, set_draft = create_signal("")

    @action
    async def add(title: str):
        set_store(lambda s: s.todos.append({"id": len(s.todos) + 1, "title": title}))
        set_draft("")

    def edit(event):
        set_draft(event.target.value)

    def submit():
        add(draft())

    def todo_row(item, index):
        return html(t"<li>{item().title}</li>")

    return html(t"""
      <div>
        <input value={draft()} oninput={edit}>
        <button onclick={submit} disabled={add.pending()}>Add</button>
        <ul>{For(store.todos, todo_row, keyed=lambda t: t["id"])}</ul>
      </div>
    """)


def failed(err, reset):
    return html(t"<div><p>Something went wrong: {str(err())}</p><button onclick={reset}>Retry</button></div>")


@component
def App():
    return Errored(
        Loading(
            html(t"""
              <main>
                <{Panel} title="Counter"><{Counter} step={2} on_change={print} /></{Panel}>
                <{Panel} title="Todos"><{Todos} /></{Panel}>
              </main>
            """),
            fallback=html(t"<p>Loading...</p>"),
        ),
        fallback=failed,
    )


render(App(), "#app")
```

Each expression that calls something or reads an attribute, such as `{count() * 2}`, `{props.title}`, or `disabled={add.pending()}`, is compiled into a getter, so it updates on its own when what it reads changes. A call in the markup such as `{Show(count() > 5, ...)}` builds the component with a getter for each dynamic argument, the way Solid passes JSX props. Event handlers are never wrapped, and named handlers read better than inline lambdas; Python needs parentheses around an inline one (`onclick={(lambda: set_open(False))}`). Use `h(tag, props, *children)` when markup is built by code; see [Templates](https://wybthon.com/concepts/templates/) and [The compiler](https://wybthon.com/concepts/compiler/).

In a project created with `wyb init`, return the root view from the entry function in `app/main.py` instead of calling `render`; the generated bootstrap renders it, or hydrates it when the page was prerendered. List routes under `prerender` in `wybthon.toml` to render them to HTML at build time. See [Server rendering](https://wybthon.com/concepts/server-rendering/).

Components are testable in plain CPython, and Wybthon's pytest plugin compiles the templates in test modules:

```python
from wybthon.testing import fire, render


def test_counter():
    with render(Counter(step=2)) as screen:
        fire.click(screen.get_by_role("button", name="+"))
        assert screen.get_by_text("Count: 2 (doubled: 4)")
```

## Documentation

Visit [wybthon.com](https://wybthon.com/) for the full documentation, including getting started guides, core concepts, API reference, working examples, and migration guides from React and Solid. Large changes are designed in [RFCs](docs/rfcs/index.md).

## Contributing

Contributions are welcome. Please see [CONTRIBUTING.md](CONTRIBUTING.md) for setup instructions, coding standards, and guidelines for submitting pull requests.

## License

[MIT](LICENSE)
