pyscript.context

Execution context management for PyScript.

This module handles the differences between running in the main browser thread versus running in a Web Worker, providing a consistent API regardless of the execution context.

Key features:

• Detects whether code is running in a worker or main thread. Read this via the boolean pyscript.context.RUNNING_IN_WORKER.
• Parses and normalizes configuration from polyscript.config and adds the Python interpreter type via the type key in pyscript.context.config.
• Provides appropriate implementations of window, document, and sync.
• Sets up JavaScript module import system, including a lazy js_import function.
• Manages PyWorker creation.
• Provides access to the current display target via pyscript.context.display_target.

Warning

These are key differences between the main thread and worker contexts:

Main thread context:

• window and document are available directly.
• PyWorker can be created to spawn worker threads.
• sync is not available (raises NotSupported).

Worker context:

• window and document are proxied from main thread (if SharedArrayBuffer available).
• PyWorker is not available (raises NotSupported).
• sync utilities are available for main thread communication.

RUNNING_IN_WORKER = not hasattr(js, 'document') module-attribute

Detect execution context: True if running in a worker, False if main thread.

config = json.loads(js.JSON.stringify(_polyscript_config)) module-attribute

Parsed and normalized configuration.

sync = None module-attribute

Sync utilities for worker-main thread communication (only in workers).

window = polyscript.xworker.window module-attribute

The window object (proxied if in a worker).

document = window.document module-attribute

The document object (proxied if in a worker).

js_import = window.Function('return (...urls) => Promise.all(urls.map((url) => import(url)))')() module-attribute

Function to import JavaScript modules dynamically.

PyWorker(url, **options)

Create a Web Worker running Python code.

This spawns a new worker thread that can execute Python code found at the url, independently of the main thread. The **options can be used to configure the worker.

from pyscript import PyWorker


# Create a worker to run background tasks.
# (`type` MUST be either `micropython` or `pyodide`)
worker = PyWorker("./worker.py", type="micropython")

PyWorker can only be created from the main thread, not from within another worker.

Source code in pyscript/context.py

def PyWorker(url, **options):
    """
    Create a Web Worker running Python code.

    This spawns a new worker thread that can execute Python code
    found at the `url`, independently of the main thread. The
    `**options` can be used to configure the worker.

    ```python
    from pyscript import PyWorker


    # Create a worker to run background tasks.
    # (`type` MUST be either `micropython` or `pyodide`)
    worker = PyWorker("./worker.py", type="micropython")
    ```

    PyWorker **can only be created from the main thread**, not from
    within another worker.
    """
    return _PyWorker(url, to_js(options))

current_target()

Get the current output target in main thread context.

Source code in pyscript/context.py

def current_target():
    """
    Get the current output target in main thread context.
    """
    return _pyscript.target