My First Gem: installing gem documentation into Dash

4 minute read

I’ve been a long time user of Most of my professional development happens on iOS, and Dash + Alfred worked their way into my workflow, even though I was previously entirely satisfied with the built-in Xcode documentation viewer. My passion / desire for code documentation goes back to the days where I’d added appledoc generation to our Xcode builds & was publishing a docset of our application code through CI. To this day, I don’t know if the handful of other devs on the project used it, nor whether it remained working for very long after I left (which yes, I know means it was probably a bad use of my time, although I think the build failures for missing documentation were a net positive).

With that said, I’ve been less impressed with Dash as soon as I left the Apple documentation. This includes moderate usage of 3rd party libraries. It’s not necessarily a fault of the app, but more an expectation from me that I shouldn’t have to manage documentation. When you’re doing mostly vanilla Apple frameworks, enough functionality is built in. Apple’s documentation, while sometimes badly lacking, does a fair job at marking API availability and it’s possible to use the latest SDK to develop against older versions of the OS.

What I really, really want is to be able to view all the documentation for a project, and only the documentation for that project. Dash has “Search Profiles” that can be manually managed: adding / removing / updating docsets, and making it easy to constrain a search to a specific profile. I’ve done that when I primarily work on a single project: here’s the iOS docs and here are the handful of libraries it currently uses, which are updated infrequently. It 99% does not work for random projects that I find and want to make a change or two to. I have been super frustrated trying to poke at random Ruby projects, and trying to look up symbols. I think some of the problem is that other ecosystems are pretty granular, some that they publish a new docset for every minor revision, and (at least with Ruby) some that when classes are extensible there are too many results (right now, searching ‘ruby: string’ gets 19 results on my machine).

Just over two weeks ago, it occurred to me that there might be a better way. What if I could programmatically update a search profile, and have it match a project’s dependencies?

Unfortunately, doesn’t expose the required APIs. You can ask for a specific docset & version to be installed, but that’s the extent of it. I’ve emailed with a feature request to do more, and the developer says it’s on his todo list.


While I was looking for a pre-existing solution, I found a ~10 line ruby script that installed all the documentation for a project’s gems, using bundler. I was able to make an immediate improvement: using open -g so that it didn’t bring to the foreground every 3 seconds.

I’d like to think I’ve improved it further, in my very first gem, bundler-install_dash_docs:

  • reads the bundler lockfile instead of executing bundle show
  • properly escapes url parameters
  • properly handles shell / system command
  • adds additional execution modes: dry-run, different verbosity options, all gems vs only dependencies

This is written as a bundler plugin, because bundler is “the” dependency management solution for Ruby. Right now it requires user action, but in theory it could be done automatically if the plugin is installed: download new version of gem && install new documentation into Dash. As a visitor to the ecosystem, I’m not sure what a perfect workflow looks like. However, I have visions of a single command loading up all the documentation for a single project, and making it searchable while excluding anything else installed on the same machine. This isn’t a bundler-specific solution: I’d immediately want the same thing for any language / ecosystem with versioned libraries that Dash knows how to fetch documentation for.

Unsupported Hack?

I poked at the custom url schemes, the (basically empty) Applescript dictionary, and concluded anything else was impossible at this stage. That’s dumb, because Dash obviously stores the Search Profile information somewhere, and with enough effort it should be possible to edit it. On my second try, I found it in ~/Library/Preferences/com.kapeli.dashdoc.plist (I think it’s odd most of the data is stored in Application Support, but this is in Preferences 🤷‍♂️).

I’ve probably scratched my itch sufficiently for now, but it’s tempting to go further.

Other languages

Why bundler? Because that’s what I was using when this occurred to me. Any combination of “versioned dependencies” and “robust Dash support” would benefit from something similar. Should it actually be a plugin to each dependency manager? Or is a Dash user going to want to install one tool that works similarly across ecosystems? (As I write that question, I feel like the answer is obvious, and not aligned with my current work. Oh well).