Officially supported themes: TwentyXXX

My website is WordPress-backed. WordPress front-ends are called “themes”. There are official themes, released by WordPress/Automattic. And there are thousands of themes released by third parties. While the WordPress project has released many themes, not all of them are equally “important”. There is only one specific series of WordPress themes that is so-to-say most official: themes from the TwentyXXX series.

The issue: no update release notes

In this series, WordPress releases one theme per year (there was TwentyEleven, TwentyTwelve, TwentyThirteen, you get the point). The most recent one of these themes is included with every major release of WordPress. In other words: it does not get more official. Correspondingly, themes from this series enjoy long-term support by the WordPress project. That is, they retrieve maintenance updates even years after their initial release (TwentyEleven was last updated by the end of 2014, for instance). That is great, really! However, there is one very negative aspect with these updates: there are no official release notes. That’s horrible, thinking in engineering terms, and considering release ethics applied in other serious open source software projects.

Background: dependency hell

TwentyXXX theme updates are released rather silently: suddenly, the WordPress dashboard shows that there is an update. But there is no official change log or release note which one could base a decision on. Nothing, apart from an increased version number. That is different from updating WordPress plugins, where the change log usually is only one click away from the WordPress dashboard. Also, the theme version number can not be relied upon to be semantically expressive (AFAIK WordPress themes are not promised to follow semantic versioning, right?)

Now, some of you may think that newer always is better. Just update and trust the developers. But that is not how things work in real life. Generally, we should stick to the paradigm of “never change a running system”, unless […]: sometimes, an update might change behavior, which might not be desired. Sometimes an update might fix a security issue, which one should know about and update immediately. Or the update resolves a usability issue. Such considerations are true for updates for any kind of software. But, in the context of WordPress, there is an even more important topic to consider when updating a theme: an update might break child themes. Or, as expressed by xkcd: “Every change breaks someones workflow”:

A theme can be used by other developers, as a so-called parent theme, in a library fashion — it provides a programming interface. This affects many websites, like mine: a couple of years ago I have decided to base the theme used on my website (here) on the TwentyTwelve theme. I went ahead and created a child theme, which inherits most of its code from TwentyTwelve and changes layout and behavior only in a few aspects. I definitely cannot blindly press the “update” button when TwentyTwelve retrieves an update. This might immediately change the interface I developed my child against, and can consequently break any component of my child theme. Obviously, I cannot just try this out with my live/public website. So, I have to test this update before, in a development environment which is not public.

If proper release notes were available, I could possibly skip that testing and apply such an update right away if it’s just a minor one. Or, I would be alerted that there is a security hole fixed with a breaking change in the parent theme, and I’d know that I have to quickly react and re-work my child theme so that I can safely apply the update to the parent. These things need to be communicated, like in any other open source project with a decent release policy.

Concluding remarks

Yes, there are ways to reconstruct and analyze the code changes that were made. This URL structure actually is quite helpful for generating diffs between theme versions: https://themes.trac.wordpress.org/changeset?old_path=/twentytwelve/1.4&new_path=/twentytwelve/1.6. That URL shows differences between TwentyTwelve 1.4 and 1.6. The same structure can be used for other official themes and version combinations. However, this does not replace a proper change log. WordPress is a mature, large-scale open source project with a huge developer community. Themes from the TwentyXXX series are a major component of this project. The project should provide change logs and/or release notes for every update — for compliance with expectations, and for enabling sound engineering decisions. Others want this, too:

Can any one point me to the release notes for 1.2 or a list of the applied changes? Updating from 1.1 has caused some minor, but unexpected presentation changes on one of my child themes, and I’d like to know what else has changed and what to test for before I upgrade further sites.