Today I Learned (TIL)
TIL stands for today I learned. This is a collection of small, practical things I’ve learnt while writing software, which I thought were worth remembering and sharing with other people.
If you want to follow along, these posts have their own RSS feed.
You can filter by tag: aws · http · jekyll · liquid · macos · podcasts · python · shell-scripting · sqlite · tumblr
These are the current filters.
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How to shuffle an array in a Jekyll template
If you want an array in random order, you can use the
samplefilter to get a random sample of the same size as the original array. -
Checking if a URL has changed when you fetch it over HTTP
When you make an HTTP request, you can use the
If-Modified-Sinceheader to get a 304 Not Modified if nothing has changed since your last request. -
The
opencommand can ask questionsIf you pass an argument that can’t be easily identified as a file or a URL,
openwill ask you what to do next. This may be a surprise if you were trying to use it in a script. -
Getting a boto3 Session for an IAM role using Python
Why I use Sessions in boto3, and the Python function I use to create them.
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Use the
{% raw %}tag to describe Liquid in LiquidIf you’re trying to write about using Liquid tags in a Liquid-based site, wrapping your tags in the
{% raw %}tag will prevent them being rendered. -
Use the
{% capture %}tag to assign complex strings to variablesIf you want to get a string that’s semi-complicated to construct, you can put a “mini-template” in the
{% capture %}tag to build it over multiple lines. -
Run a randomly selected subset of tests with pytest
By reading the code for the
pytest-random-orderplugin, I was able to write a new plugin that runs a random subset of tests. -
Using sqlite-utils to convert a CSV into a SQLite database
You can use sqlite-utils on the command line to create a SQLite database from a CSV file.
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Python’s sqlite3 context manager doesn’t close connections
The
sqlite3.connect(…)context manager will hold connections open, so you need to remember to close it manually or write your own context manager. -
How to set the clock on a Tricity Bendix SIE454 electric cooker
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How to set the clock on a Worcester 28CDi boiler
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Get an RSS feed of external audio posts on Tumblr
If you add
/podcastto a Tumblr site, you get a podcast-like RSS feed for all the external audio posts on that site.