Posts in July, 2018

Jul 5, 2018
in Tech

Idiomatic usage of Python assignment expressions (PEP 572)

Most PEPs (Python Enhancement Proposal) tend do go under the radar of most developers, but PEP 572 has caused a lot of controversy in the Python community, with some developers expressing an intense dislike for the new syntax (and that is sugar coated).

Personally, I don't think it deserves the vitriol it received, and I'm looking forward to its addition in Python 3.8.

So what are assignment expressions? Currently in Python assignments have to be statements, so you can do foo = bar(), but you can't do that assignment from within an if or while statement (for example). Which is why the following is a syntax error: continue reading…

Jul 5, 2018
in Tech

Compress WebSocket streams with Lomond 0.3.2

I've recently released version 0.3.2 of Lomond, a WebSocket client for Python with a focus on correctness and ease-of-use.

The major feature of the 0.3 release is per-message compression, which allows for text and binary to be sent in compressed form.

Here's a modified version of the Bitcoin price ticker example which enables compression. This spews every trade made on the GDax platform:

Using the per-message compression extension to the WebSocket spec with Lomond.

That's a lot of data coming through the WebSocket, which fortunately compresses very well.

Also in this release are a number of optimisations to reduce cpu and memory usage.

Lomond is fast approaching a 1.0 release, but is already very stable. It is part of the open source software that powers Dataplicity.