I was going through the Django Admin Cookbook today and came across the following snippet:
return ", ".join([ child.name for child in obj.children.all() ])
Reads fine but made no sense as it ditches the tabs construct that is so ubiquitous in Python. I usually don’t like such clever one-liners, but learned from it nonetheless. There’s probably more to it than I can see as a Python beginner.
Essentially, the argument passed to str.join(iterable) boils down to:
[expression for x in y]
Let’s expand that with an example:
[person.get_full_name() for person in people]
This will return a sequence (which is an iterable, and in this case a list) by running the given expression for each
person returned by the
people iterable. It returns a list because of those square brackets around the whole instruction:
So, it might return, for a more real world example, something like:
["Jim Harper", "Pam Beesly", "Kelly Kapoor", "Toby Flendorson"]
Update: As Jason McGillivray and Nicola Zangrandi informed me on Mastodon and Twitter respectively, the technical name for this “pattern” is actually list comprehension!
Join the discussion on Mastodon or Twitter.