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Merge pull request #99 from pyscript/2024-5-2
Update docs to 2024.5.2 version
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‎README.md‎

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Welcome to the PyScript documentation repository.
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This source code becomes the official PyScript documentation hosted here:
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[https://docs.pyscript.net](https://docs.pyscript.net/)
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Contribute prose and participate in discussions about the written support of
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PyScript and related topics.
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## Getting started
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Before you start contributing to the documentation, it's worthwhile to
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take a look at the general contributing guidelines for the PyScript project. You can find these guidelines here
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take a look at the general contributing guidelines for the PyScript project.
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You can find these guidelines here
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[Contributing Guidelines](https://github.com/pyscript/pyscript/blob/main/CONTRIBUTING.md)
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## Setup
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The `docs` directory in the pyscript repository contains a
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[Material for MkDocs](https://squidfunk.github.io/mkdocs-material/) documentation project. Material is a system
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that takes plaintext files containing documentation written in Markdown, along with
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static files like templates and themes, to build the static end result.
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[Material for MkDocs](https://squidfunk.github.io/mkdocs-material/)
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documentation project. Material is a system that takes plaintext files
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containing documentation written in Markdown, along with static files like
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templates and themes, to build the static end result.
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To setup the documentation development environment simply create a new
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virtual environment, then `pip install -r requirements.txt` (from in the root
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## Cross-referencing
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You can link to other pages in the documentation by using the `{doc}` role. For example, to link to the `docs/README.md` file, you would use:
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Link to other pages in the documentation by using the `{doc}` role. For
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example, to link to the `docs/README.md` file, you would use:
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```markdown
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{doc}`docs/README.md`
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```
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You can also cross-reference the python glossary by using the `{term}` role. For example, to link to the `iterable` term, you would use:
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Cross-reference the Python glossary by using the `{term}` role. For example, to
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link to the `iterable` term, you would use:
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```markdown
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{term}`iterable`
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```
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You can also cross-reference functions, methods or data attributes by using the `{attr}` for example:
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Cross-reference functions, methods or data attributes by using the `{attr}` for
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example:
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```markdown
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{py:func}`repr`

‎docs/beginning-pyscript.md‎

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<meta charset="utf-8" />
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<meta name="viewport" content="width=device-width,initial-scale=1" />
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<title>🦜 Polyglot - Piratical PyScript</title>
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<link rel="stylesheet" href="https://pyscript.net/releases/2024.5.1/core.css">
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<script type="module" src="https://pyscript.net/releases/2024.5.1/core.js"></script>
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<link rel="stylesheet" href="https://pyscript.net/releases/2024.5.2/core.css">
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<script type="module" src="https://pyscript.net/releases/2024.5.2/core.js"></script>
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</head>
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<body>
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<meta charset="utf-8" />
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<meta name="viewport" content="width=device-width,initial-scale=1" />
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<title>🦜 Polyglot - Piratical PyScript</title>
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<link rel="stylesheet" href="https://pyscript.net/releases/2024.5.1/core.css">
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<script type="module" src="https://pyscript.net/releases/2024.5.1/core.js"></script>
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<link rel="stylesheet" href="https://pyscript.net/releases/2024.5.2/core.css">
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<script type="module" src="https://pyscript.net/releases/2024.5.2/core.js"></script>
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</head>
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<body>
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<h1>Polyglot 🦜 💬 🇬🇧 ➡️ 🏴‍☠️</h1>

‎docs/faq.md‎

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workers are limited to one way calls from the main thread to methods
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exposed by workers.
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If `sync_main_only = True`, the following caveats apply:
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If `sync_main_only = true`, the following caveats apply:
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* It is not possible to manipulate the DOM or do anything meaningful on the
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main thread **from a worker**. This is because Atomics cannot guarantee
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While such legacy code exists, be aware that JavaScript code may require
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special care.
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### Possible deadlock
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Users may encounter an error message similar to the following:
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!!! failure
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```
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💀🔒 - Possible deadlock if proxy.xyz(...args) is awaited
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```
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#### When
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This error happens when your code on a worker and in the main thread are
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[in a deadlock](https://en.wikipedia.org/wiki/Deadlock). Put simply, neither
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fragment of code can proceed without waiting for the other.
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#### Why
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Let's assume a worker script contains the following Python code:
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```python title="worker: a deadlock example"
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from pyscript import sync
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sync.worker_task = lambda: print('🔥 this is fine 🔥')
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# deadlock 💀🔒
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sync.main_task()
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```
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On the main thread, let's instead assume this code:
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```html title="main: a deadlock example"
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<script type="mpy">
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from pyscript import PyWorker
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def async main_task():
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# deadlock 💀🔒
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await pw.sync.worker_task()
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pw = PyWorker("./worker.py", {"type": "pyodide"})
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pw.sync.main_task = main_task
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</script>
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```
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When the worker bootstraps and calls `sync.main_task()` on the main thread, it
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blocks until the result of this call is returned. Hence it cannot respond to
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anything at all. However, in the code on the main thread, the
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`sync.worker_task()` in the worker is called, but the worker is blocked! Now
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the code on both the main thread and worker are mutually blocked and waiting
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on each other. We are in a classic
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[deadlock](https://en.wikipedia.org/wiki/Deadlock) situation.
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The moral of the story? Don't create such circular deadlocks!
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How?
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The mutually blocking calls cause the deadlock, so simply don't block.
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For example, on the main thread, let's instead assume this code:
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```html title="main: avoiding deadlocks"
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<script type="mpy">
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from pyscript import window, PyWorker
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async def main_task():
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# do not await the worker,
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# just schedule it for later (as resolved)
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window.Promise.resolve(pw.sync.worker_task())
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pw = PyWorker("./worker.py", {"type": "pyodide"})
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pw.sync.main_task = main_task
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</script>
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```
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By scheduling the call to the worker (rather than awaiting it), it's possible
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for the main thread to call functions defined in the worker in a non-blocking
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manner, thus allowing the worker to also work in an unblocked manner and react
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to such calls. We have resolved the mutual deadlock.
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## Helpful hints
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This section contains common hacks or hints to make using PyScript easier.

‎docs/user-guide/configuration.md‎

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[numberwang](https://numberwang.readthedocs.io/en/latest/) are installed from
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PyPI (the [Python Packaging Index](https://pypi.org/)):
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```TOML title="Configuration via TOML"
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```TOML title="Configuration via TOML."
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packages = ["arrr", "numberwang" ]
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```
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```JSON title="Configuration via JSON"
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```JSON title="Configuration via JSON."
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{
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"packages": ["arrr", "numberwang"]
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}
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If you use JSON, you can make it the value of the `config` attribute:
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```HTML title="JSON as the value of the config attribute"
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```HTML title="JSON as the value of the config attribute."
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<script type="mpy" src="main.py" config='{"packages":["arrr", "numberwang"]}'></script>
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```
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For historical and convenience reasons we still support the inline
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specification of configuration information via a _single_ `<py-config>` or
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`<mpy-config>` tag in your HTML document:
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```HTML title="Inline configuration via the &lt;py-config&gt; tag"
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```HTML title="Inline configuration via the &lt;py-config&gt; tag."
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<py-config>
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## Options
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There are four core options ([`interpreter`](#interpreter), [`files`](#files),
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[`packages`](#packages), and
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[`js_modules`](#javascript-modules)) and an experimental flag
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([experimental_create_proxy](#experimental_create_proxy)) that can be used in
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There are five core options ([`interpreter`](#interpreter), [`files`](#files),
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[`packages`](#packages), [`js_modules`](#javascript-modules) and
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[`sync_main_only`](#sync_main_only)) and an experimental flag
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([`experimental_create_proxy`](#experimental_create_proxy)) that can be used in
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the configuration of PyScript. The user is also free to define
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arbitrary additional configuration options that plugins or an app may require
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for their own reasons.
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The following two examples are equivalent:
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```TOML title="Specify the interpreter version in TOML"
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```TOML title="Specify the interpreter version in TOML."
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interpreter = "0.23.4"
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```
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```JSON title="Specify the interpreter version in JSON"
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```JSON title="Specify the interpreter version in JSON."
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{
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"interpreter": "0.23.4"
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}
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The following JSON fragment uses a fully qualified URL to point to the same
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version of Pyodide as specified in the previous examples:
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```JSON title="Specify the interpreter via a fully qualified URL"
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```JSON title="Specify the interpreter via a fully qualified URL."
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{
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"interpreter": "https://cdn.jsdelivr.net/pyodide/v0.23.4/full/pyodide.mjs"
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}
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The following JSON and TOML are equivalent:
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```json title="Fetch files onto the filesystem with JSON"
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```json title="Fetch files onto the filesystem with JSON."
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"files": {
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"https://example.com/data.csv": "./data.csv",
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}
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```
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```toml title="Fetch files onto the filesystem with TOML"
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```toml title="Fetch files onto the filesystem with TOML."
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[files]
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"https://example.com/data.csv" = "./data.csv"
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"/code.py" = "./subdir/code.py"
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the content is copied. As a result, the `data.csv` entry from the previous
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examples could be equivalently re-written as:
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```json title="JSON implied filename in the root directory"
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```json title="JSON implied filename in the root directory."
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{
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"files": {
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"https://example.com/data.csv": "",
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```
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```toml title="TOML implied filename in the root directory"
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```toml title="TOML implied filename in the root directory."
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[files]
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"https://example.com/data.csv" = ""
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The following JSON and TOML are equivalent:
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```json title="Using the template language in JSON"
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```json title="Using the template language in JSON."
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{
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"files": {
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"{DOMAIN}": "https://my-server.com",
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```
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```toml title="Using the template language in TOML"
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```toml title="Using the template language in TOML."
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[files]
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"{DOMAIN}" = "https://my-server.com"
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"{PATH}" = "a/path"
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The following two examples are equivalent:
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```TOML title="A packages list in TOML"
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```TOML title="A packages list in TOML."
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packages = ["arrr", "numberwang", "snowballstemmer>=2.2.0" ]
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```
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```JSON title="A packages list in JSON"
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```JSON title="A packages list in JSON."
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{
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"packages": ["arrr", "numberwang", "snowballstemmer>=2.2.0" ]
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}
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For example, to use the excellent [Leaflet](https://leafletjs.com/) JavaScript
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module for creating interactive maps you'd add the following lines:
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```TOML title="JavaScript main thread modules defined in TOML"
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```TOML title="JavaScript main thread modules defined in TOML."
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[js_modules.main]
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"https://cdn.jsdelivr.net/npm/leaflet@1.9.4/dist/leaflet-src.esm.js" = "leaflet"
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"https://cdn.jsdelivr.net/npm/leaflet@1.9.4/dist/leaflet.css" = "leaflet" # CSS
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```
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```JSON title="JavaScript main thread modules defined in JSON"
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```JSON title="JavaScript main thread modules defined in JSON."
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{
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"js_modules": {
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"main": {
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access to the DOM and, for efficiency reasons, can be included in the worker
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context:
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```TOML title="A JavaScript worker module defined in TOML"
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```TOML title="A JavaScript worker module defined in TOML."
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[js_modules.worker]
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"https://cdn.jsdelivr.net/npm/html-escaper" = "html_escaper"
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```
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```JSON title="A JavaScript worker module defined in JSON"
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```JSON title="A JavaScript worker module defined in JSON."
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{
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"js_modules": {
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"worker": {
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However, `from pyscript.js_modules import html_escaper` would then only work
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within the context of Python code **running on a worker**.
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### sync_main_only
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Sometimes you just want to start an expensive computation on a web worker
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without the need for the worker to interact with the main thread. You're simply
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awaiting the result of a method exposed from a worker.
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This has the advantage of not requiring the use of `SharedArrayBuffer` and
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[associated CORS related header configuration](../workers/#http-headers).
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If the `sync_main_only` flag is set, then **interactions between the main thread
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and workers are limited to one way calls from the main thread to methods
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exposed by the workers**.
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```TOML title="Setting the sync_main_only flag in TOML."
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sync_main_only = true
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```
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```JSON title="Setting the sync_main_only flag in JSON."
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{
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"sync_main_only": true
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}
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```
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If `sync_main_only` is set, the following caveats apply:
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* It is not possible to manipulate the DOM or do anything meaningful on the
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main thread **from a worker**. This is because Atomics cannot guarantee
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sync-like locks between a worker and the main thread.
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* Only a worker's `pyscript.sync` methods are exposed, and **they can only be
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awaited from the main thread**.
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* The worker can only `await` main thread references one after the other, so
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developer experience is degraded when one needs to interact with the
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main thread.
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### experimental_create_proxy
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Knowing when to use the `pyscript.ffi.create_proxy` method when using Pyodide

‎docs/user-guide/first-steps.md‎

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<meta charset="UTF-8">
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<meta name="viewport" content="width=device-width,initial-scale=1.0">
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<!-- PyScript CSS -->
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<link rel="stylesheet" href="https://pyscript.net/releases/2024.5.1/core.css">
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<link rel="stylesheet" href="https://pyscript.net/releases/2024.5.2/core.css">
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<!-- This script tag bootstraps PyScript -->
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<script type="module" src="https://pyscript.net/releases/2024.5.1/core.js"></script>
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<script type="module" src="https://pyscript.net/releases/2024.5.2/core.js"></script>
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</head>
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<body>
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<!-- your code goes here... -->

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