Simon Rentzke

Blue Blistering Barnacles

Most recent git branches

Sometimes I work on a few branches at the same time.

Emergency bug fix branch here, new feature branch there, performance update branch here, update gem branch there, etc...

Within a big project we sometimes have almost 40 branches at any one time.

So, being human I forget the name of the branch that I was working on last week, and also would like to clean up old branches that I no longer need.

So the solution git for-each-ref

Include a sort and formatting that includes last commit date, and author name. This is the command:

git for-each-ref --count=30 --sort=-committerdate refs/heads/ --format='%(refname:short) %(committerdate) %(authorname)'

Home Entertainment

Recently I have been investigating what the cheapest/easiest setup could be for a home entertainment system would be.

I have an old Macbook laptop that doesn't have a working touchpad and keyboard - but everything else works, so am using that as a media server.

So, my favourite combination of Software/Hardware is:

  • Plex Server, easy to setup, works on all operating systems. You can add your own specific custom plugins, for example ABC iview in Australia, just look on GitHub.

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  • Chromecast - best $30 spent ever. Really simple device that works insanely well. Even without a media server, you can get some fantastic apps on your mobile - and cast from there.

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  • Plex mobile app ~$6, enables you to browse your Plex channels, and cast to your TV. Works on iPad, iPhone and Android.

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Now all I need is a decent live sports channel, and I'll be set.

Best Coffee Shops to work from in San Francisco

You'll see the Nodes, Rubies, the GitHubs, and get power points (mostly). Plus great Coffee.

Not too much VC raising - app idea BS either.

Ritual Coffee

1989 - 1996 : The Golden Years

James Blake - Retrograde

First Lesson: Drawing a diamond with Ruby

I was reminiscing recently about what my programming exercises were at high school. I started on Turbo Pascal.

This is was one of the first, simply to draw a diamond shape, that looked like this:


I remember it taking forever, but loving it. So decided to write it out in ruby.

s = 10
(-s..s+1).each do |y|
  (-s..s+1).each do |x|
   print x.abs + y.abs > s ? ' ' : '*'

Alternative solution: s = 10 s.times {|u| puts ' ' * (s - u.to_i) + '*' * (u + u.to_i) } s.downto(0).each {|u| puts ' ' * (s - u.to_i) + '*' * (u + u.to_i) };

Slime Mould Maze

Recently I attended a workshop at the Edge on 3D printing and slime mould.

The event's title was so whack, that I signed up - not knowing what to expect.. This is what we did:

First, an intro to 3D printing. We create a maze in TinkerCad

TinkerCad, was until recently going to shut down, but luckily AutoDesk bought them out.

It's a fantastic way to ease into CAD, and produce 3D printable things. Within 5 minutes I grasped how to use it. Super simple.


Then we made some Agar, chucked the 3D maze in to a petrie dish, and dropped a piece of ravenous slime mould into the middle of it, with some rolled oats.

slime mould

Then I hid my slime mould in a dark box, and 2 days later - my simple maze looked like this - solved!

slime mould solved maze

This is a fascinating timelapse video, of slime mould's ability to actually solve the maze intelligently.

La Haine - Assassin de la police

Quickest way to determine the state of a rails app?

As a contractor, I'll never say yes to a project before doing a code review. Saying that, I still enjoy taking on disaster code bases. But in order to manage expectations from both sides, this is my TODO list of things to check and report back on, before saying yes.


  • Does it have a Gemfile?
  • Does it use a README?
  • Does the seed file work?
  • Do the migrations or schema.rb work?


  • Does it have any?
  • Do they pass?
  • Does it test the model logic?
  • Do they use a CI server?


  • Do they have have decent commit messages?
  • Are there models/controllers that aren't used anymore?
  • Are there decent comments?
  • Do they store passwords in plain text (you'd be suprised)?


  • How big is the team?
  • Is there a product owner?
  • Do they have a future plans, or do they need you for putting out fires?
  • Do they have a bug tracker?
  • Do they have a task board?
  • Are you going to be responsible for support calls?

8 Steps to become a Web Programmer

My brother asked me about how to get something on the web. "Should I use wordpress?"; "Should I use Joomla?", "Should I use ...."

I figured it'd be so much more valuable to take the time to learn the basics of the web. So I quickly jotted down a few steps on how to start out and then gradually move on to the more grungy world of programming.

Step 1: Basics of HTML, CSS

Know how to create basic markup, and stylesheets. In order to learn this I'd start by creating a personal page, for example your Resume/CV. Don't use a fancy editor, use Notepad++(PC), or Textmate(Mac) or my favourite Sublime Text.

If you'd like more info on HTML have a read through Dive into HTML5

Step 2: Advanced CSS

Get a simple understanding of each CSS feature

Step 3: Push it live to the world

Sign up to Github, and push your html site to GitHub pages.

Step 4: Learn a Clean Programming Language

If you've got the hang of the last few steps, you'll be itching to learn more of the more grungy stuff. So I'd kick off by learning a beautiful language like Python or Ruby. I would start with the wonderful TryRuby

But here is a comprehensive list if you arent comfortable with that 'best ways to teach a beginner to program'

5. Step 5:

Get an account, start asking questions. Programmers are amazingly willing to help everyone in the community.

Step 6: Server Side Web

Pick a server side web language like php, ruby, python. I'd recommend Ruby on Rails a web framework. Try and build something simple that has the need for storing data on the server, for example a blog.

Step 7: Javascript/Jquery

Go back to the Web. Learn the basics of javascript, and if you get bored get some knowledge of jQuery, and learn all the magical things you can do on the client side. Check out the Mozilla Developer Network

Step 8: Database

Learn the basics of SQL, and have a play with entity relationships, has-many, and one-to-many relationships. I'd use sqlite, or postgreSQL.