October 2013 Meeting

The October 2013 meeting of LRUG will be on Monday the 14th of October, from 6:30pm to 8:00pm. Our hosts Skills Matter will be providing the space, at their offices on Goswell Road; The Skills Matter eXchange. Registration details are given below.


Modelling state machines with Ragel

Drew Neil wants to talk to us about Ragel:

Ragel is a State Machine Compiler, which can generate Ruby code (as well as C, Java, Go, and more). It can be used for writing robust protocol implementations, parsing data formats, and performing lexical analysis of programming languages. Ragel is used in many open source projects including Gherkin, Thin, Min, Mongrel, Redcloth, Radiant, and Hpricot.

To demonstrate Ragel's capabilities we'll model Vim, which is a Finite State Machine. We'll do so by parsing a stream of Vim keystrokes, using Ragel state machines to manage the transitions between Vim's modes. We'll see how to generate state chart visualisations with Ragel, and how these can be used to debug our state machines. The resulting program will enable us to analyse and visualise the interactions of a Vim user.

  1. Code used in presentation
  2. Modelling State Machines with Ragel
  3. Skills Matter : London Ruby User Group : Modelling state machines with Ragel

Enumerators in Ruby

Olly Legg says:

Enumerators are a little known class in the standard library. I'll discuss where they're used in stdlib, how you can implement them and (at least) one practical example where they might be the right solution.

  1. Examples of using Enumnerators: paginated_collection.rb
  2. Enumerators
  3. Skills Matter : London Ruby User Group : Enumerators in Ruby


How Are You?

During the talks there will be some drinks available (alcoholic and soft), provided by the nice folks at How Are You?.


Skills Matter?

During the talks there will be some pizzas available (vegetarian & vegan options available), provided by our hosts Skills Matter.


After the talks the evening continues in a more informal style at The Slaughtered Lamb. It's a great place to discuss the talks directly with the speakers, or chat to other rubyists about the great debates of the day. If you are unable to make the talks, for whatever reason, do feel free to turn up for this part of the evening. We're usually jostling for space at the bar from around 8pm.


To secure a place at the meeting you must register with our hosts Skills Matter. It helps to make sure we have the room laid out with enough chairs, and in extreme cases that we get priority on the larger rooms over other groups using the space on the same night. Also, it's polite (don't forget MINASWAN), so please do register with Skills Matter.

You can also follow this meeting on lanyrd, but this is not a meaningful way to tell Skills Matter you wish to attend. It's just for the lols, innit?

Posted by Murray Steele on Sep 16, 2013