DBussy + GLib Event Loop

Lawrence D'Oliveiro ldo at geek-central.gen.nz
Thu Oct 5 22:42:38 UTC 2017

DBussy <https://github.com/ldo/dbussy>, <https://gitlab.com/ldo/dbussy>
is my Python binding for libdbus that takes advantage of the asyncio
<https://docs.python.org/3/library/asyncio.html> event-loop framework
with the coroutine capability introduced with Python 3.5.

Of course, every GUI toolkit already defines its own event loop. For
example, GTK+ is built around one provided by GLib
And nobody is going to replace their event loop with Python’s one.

But they don’t need to. asyncio provides a default event loop, but more
than that, it defines a standard event-loop API. And it doesn’t really
require that much work to take an existing event loop and wrap it to be
compatible with this API, as a subclass of asyncio.AbstractEventLoop.
And then a GUI toolkit event loop that knows nothing of coroutines,
originally written for a language that had no such capability, becomes
capable of supporting coroutines in Python.

For example, glibcoro <https://github.com/ldo/glibcoro>,
<https://gitlab.com/ldo/glibcoro> is my attempt at an
asyncio-compatible layer wrapping the GLib event loop. So far it is
about 370 lines of code, which is not a large amount. And it is
functional enough to run these coroutine-intensive examples
<https://gitlab.com/ldo/glibcoro_examples>, which include a couple
showing off the usefulness of coroutines in a GUI-based app.

A new example I just added to this repo is a version of the
D-Bus signal_listener script from my collection of examples of DBussy in
action. Like the other non-GUI examples, it can run with either event
loop, just by setting an environment variable, to demonstrate that the
behaviour is just about identical either way. (Can you find any

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