In case you haven’t figured out yet that I write stuff here as much for myself as for anyone else, well, its true. Almost every single day I find myself going back to my own blog as a reference tool. Today I’m writing a part two to my Working with the Gem Ecosystem post.

My thanks are extended to Nick who helped clarify the Gem update process and pointed out the need to embed the branch name in the Gemfile. He picked this up from his work on the Orats gem which is very useful if you’re into Rails and Docker.


I’m a big believer in custom generators and I’ve always found the process of writing them to be convoluted at best. I recently found pattern_generator which makes writing generators drop dead easy. I’m writing a project now where a major part of the process is writing custom data parsers for all kinds of web sites – udemy, leanpub, pluralsight, instagram, etc. These are all PORO (plain old ruby objects) i.e. no ActiveRecord backed and I wanted a custom generator which:

  • created my class
  • created my template
  • filled out the boilerplate structure

Happily pattern_generator is just plain perfect. Here’s all I did

  • fork the gem
  • clone it to my computer
  • open it in an editor
  • create a directory
  • add my template class
  • add my template spec
  • replace the class name with erb style output tags

And while this worked great, I ran into issues when I started making changes …

Note: The issues I had here are mine and mine alone. Sung Won Cho did a great job on pattern_generator and I thank him for it.

And Now Back to Gems

My problem came when I added my fork of pattern_generator to my project’s Gemfile and did a bundle install. At first the gem came down perfectly but I noticed a few bugs. I then updated my code and re-bundled and nothing. I didn’t get any of my changes. Here’s how I had it in my Gemfile initially:

gem 'pattern_generator', :git => ''

Naturally this was located in a development only section of the Gemfile since we don’t want the memory overhead of this in production.

My first thought was that this was tied to a bundle update versus bundle instlal so I did:

bundle update

And, again, nothing. Next I tried:

bundle update –source=

I would have expected a bundle update pattern_generator to work but I did not find that to be the case. But even with specifying the source explicitly I still did not get the right version of my code. Happily Nick and I were about to pair anyway so I asked him and he honed right in on the branch i.e. specify the branch in the Gemfile. Here’s how that looks:

gem 'pattern_generator', :git => '', :branch => "master"

And that worked perfectly. I wrote several new parsers today and then used my SyncDotRake toolkit to merge the parsing code into a new Service Oriented API. Overall it was a damn good day. Thanks Nick!

Note: I next updated the gem on the following day and could not get it to update at all. I finally tried:

bundle update pattern_generator

and that actually seemed to work consistently and reliably.