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Code

A collection of 40 posts

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Introducing API Boundaries to Prepare for Bigger Changes

Alternatively: API Boundaries for Fun and Profit I routinely misquote Kent Beck, who said "for each desired change, make the change easy (warning: this may be hard), then make the easy change." He said this on Twitter (RIP) so I won't be linking to it, but at least for now

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Code is Knowledge

In the mid-2000s (so, in ancient history) a friend of mine went to an interview at a big tech company and was asked to write the JPEG compression algorithm on a whiteboard. He didn't know that algorithm off the top of his head, which he admitted, and then made up

Using Timers to Learn

Using Timers to Learn

When I'm trying to learn a new language or environment, one of the first things that I try to do is implement a timer: code that can be used to instrument other code and print out how long it took to run. A long time ago, early on in my

Go Interfaces as Requirements, not Capabilities

This is a hard-won lesson that's taken me many years to learn, and I have seen others follow a similar path, so I'm writing it down in hopes that maybe some people will find a shortcut. Go's type system is, in my experience, fairly unique. There's a family of object-oriented

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Changing the Meaning: Breaking Semantic Changes

The subtlest kind of breaking change is the kind that doesn't affect a value's type but instead affects what that value means. These changes can be hard to notice when you're making them, and even harder to debug when they happen. They can lead to downstream effects like broken reports—

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Constrain Your Data Access for Fun and Scale

ActiveRecord-style ORMs can be huge time-savers, but also blur boundaries within a system, which leads to bad assumptions and habits

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Building Extensibility into APIs from the Start

Making the right design decisions early in a project can have a huge impact on the ability to safely improve and evolve it over time.

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In defense of unit tests

A few years back, Guillermo Rauch—now the CEO of Vercel—tweeted a pithy assessment of automated testing: Write tests. Not too many. Mostly integration. — Guillermo Rauch (@rauchg) December 10, 2016 This inspired Kent C. Dodds to write that: Integration tests strike a great balance on the trade-offs between confidence

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continuous deployment

Sliding Windows of Compatibility

Writing software professionally means constantly changing, evolving, and migrating applications. All-new "greenfield" projects are a rare treat, but not the norm. Constant change means we have to be comfortable making big changes applications that are running in production environments, usually with customers using them, and do it safely, without downtime

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Caller-controlled Rollouts

Slightly warm take warning: not everything needs to be feature-flagged. New APIs or API endpoints, for example, that have no callers yet, don't benefit from the ability to toggle them off. If nothing is executing this code, then there's no behavior to disable. Let's say we have an API for

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Open Source Subway Map

If you don't actually want to read this whole post (no shame at all) the tl;dr is that I'm going to try using a GitHub project to organize and hold myself accountable for open source maintenance. Mental health is a weird thing, sometimes. Like, oh I don't know, everyone,

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What is "Tech Depreciation?"

As soon as you drive that software off the lot, its value will start going down. "Tech debt" is a well-known and useful metaphor, but I've found it doesn't describe the whole picture. Technical debt is a choice, a trade-off—sometimes made well—that can be paid down. It describes

Open Source Update: Waffle

I just pushed version 0.11 of Waffle [https://pypi.python.org/pypi/django-waffle/0.11], the feature flipper for Django [https://www.djangoproject.com/]. It contains a number of code and documentation fixes [https://github.com/jsocol/django-waffle/compare/v0.10.1...v0.11] which you can also see

Open Source Update: Bleach

As of today, I transferred ownership of Bleach [https://github.com/mozilla/bleach] to the Mozilla organization, and the Mozilla WebDev team, in particular Will Kahn-Greene [http://bluesock.org/~willkg/] and Jannis Leidel [https://twitter.com/jezdez/], are taking over maintenance of it. Huge thanks to Will, Jannis and Chris

Bounties and Tips

Last week [https://coffeeonthekeyboard.com/biweekly-ish-update-07nov2014-1185/] I wandered into the tip4commit fracas [https://news.ycombinator.com/item?id=8542969] and a “helpful” commenter pointed out Bountysource, so I started asking some questions there. There must have been a few others doing the same thing because, to their credit, they started

Simple out-of-process lock with Python and Memcached

On TodaysMeet [https://todaysmeet.com/] I need to check that a name is not in use before creating a new record. Unfortunately, because names can be reused over time, I can’t create a UNIQUE key in the database and enforce it there. That means there is some tiny amount

Actually Starting an Open Source Project

I’m a little late to the party, but I just got around to reading Starting an Open-Source Project [http://coding.smashingmagazine.com/2013/01/03/starting-open-source-project/] and, as someone who has started several reasonably successful projects, I wanted to publicly disagree with, essentially, the entire article. The article outlines

Where are James' Slides?

I give a lot—well, I give some—talks, but I never give the slides out. And, as far as I can remember, no one has ever asked for them. I know people, people who speak a lot more than me [http://stevesouders.com/], who put all their slide decks

Why Django Sucks, Except When It Doesn't

Ken Reitz [https://twitter.com/kennethreitz] is a smart man. Very smart. Smarter than me. He’s responsible for some of the best [https://github.com/kennethreitz/flask-sslify], most widely-used [https://crate.io/packages/requests/] Python libraries out there. So when he talks, I listen. And recently, he talked about

Developing at Scale: Database Replication

When a website is small—like this one, for example—usually the entire thing, from the web server to the database, can live on a single server. Even a single virtual server. One of the first things that happens when a web site gets bigger is this is no longer

Code-sharing Update

When we decided to move SUMO to a new platform [https://coffeeonthekeyboard.com/the-evolution-of-sumo-339/], one of the reasons we chose Django [http://www.djangoproject.com/] was code sharing and reuse—specifically that SUMO [http://support.mozilla.com/] and AMO [https://addons.mozilla.org] would be able to share code, meaning

Widget l10n

I spent some of today working on bringing a couple of WordPress widgets up-to-date (Better Search [http://jamessocol.com/projects/better-search-widget.php] and Most Comments [http://jamessocol.com/projects/most-comments-widget.php]) only to discover there is a new widget API [http://codex.wordpress.org/Widgets_API#Developing_Widgets_on_2.

JavaScript: Private Static Members, Part 2

Finally, it’s time to finish up the lesson on private static members and methods in JavaScript. Last time [https://coffeeonthekeyboard.com/javascript-private-static-members-part-1-208/], I introduced the technique of creating and immediately executing a function, using parentheses. I talked a little about returning a function and storing it in a variable.

JavaScript: Private Static Members, Part 1

A little while ago [https://coffeeonthekeyboard.com/private-variables-in-javascript-177/] I talked about creating private variables and methods in JavaScript. This works, but is not necessarily efficient: each instance of the class creates new copies of the members. While that may be exactly what you want for instance variables (think of partNum