abstraction-watch

abstraction-watch, in Python

Be told what is true now, and be told when nothing has changed for a while. A Notice carries the present; quiet says nothing visible has moved for at least the budget, and silence says for how long. One module, standard library only, importing nothing of ours.

Quiet is the half that is normally missing. A progress bar that stops moving and a transfer nobody is performing look identical to a listener that is only told about changes.

This page is the Python package. The contract, the Go and C++ implementations, what is measured and what is UNPROVEN are on the repository.

Install

Not on PyPI, and the name on PyPI is not ours.

git clone https://github.com/openabstractions/abstraction-watch
pip install ./abstraction-watch/python

Python 3.9 or later. abstraction_watch.py is one file with no imports of ours, so copying it into a _vendor/ directory of your own is an equally complete installation.

An example that runs

A source that says when it moved, and a listener that hears both the change and the quiet after it:

import abstraction_watch as watch

progress = watch.push({"done": 0}, stamp="0", budget=0.5)
progress.post({"done": 1 << 20}, stamp="1")

notice = progress.next()
print("now:", notice.now)

notice = progress.next()
print("quiet:", notice.quiet, "after", round(notice.silence, 1), "s of nothing")
progress.close()

budget=0.5 is the quiet budget and the only timer here: the listener's own wait decides when silence counts, so a change the source already made is always delivered ahead of a quiet that would postdate it.

What an application calls

A subscription is iterable: for notice in subscription: ..., ending on close(). stamp is what decides whether a value is a change; two reads with the same stamp are one.

abstraction_job.watch(store, kind, budget) is this primitive with a job store as the source, which is what a download progress view binds to.

What may break

• No conformance verdict, in any language. No scenario in the suite cites this layer yet — what is proven and what is not. Anything that depends on this layer inherits that.
• Not on any package index, and no release carries an API stability promise. Pin a commit you have read.
• poll asks; it does not subscribe to the platform. There is no inotify, no ReadDirectoryChangesW and no FSEvents under it. settle is the seam where a caller supplies those.
• Every published transcript was produced on Windows or Linux. macOS is UNPROVEN throughout.

Apache-2.0. See LICENSE.