Software Engineering Radio

Recording Venue: JAOO 2006
Guest(s): Obie Fernandez
Host(s): Markus
In this episode, we’re talking to Obie Fernandez about agile DSL development in Ruby. We started our discussion by defining what a DSL is, the difference between internal and external DSLs as well as the importance of the flexibly syntax of the host language in order to make DSLs worthwhile. We then looked at a couple of real world examples for DSLs, specifically, at Business Natural Languages. We then progressed to the main part of the discussions, which centered around the features of Ruby that are important for building DSLs. These include the flexible handling of parentheses, symbols, blocks as well as literal arrays and hashes. We then discussed Ruby’s meta programming feautures and how they are important for building DSLs: instantiation, method_missing callback, class macros, top level
functions and sandboxing. Features like eval, class_eval, instance_eval and define_method are also important for DSLs in
Ruby, as well as using alias_method for simple AOP.

Links:

• The slides on which this episode is based
• Martin Fowler’s article on Language Workbenches
• Obie’s Web Site

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Recording Venue: OOPSLA 2006
Guest(s): Niclas Nilsson
Host(s): Markus
In this Episode we talk about dynamic languages for statically-typed minds, or in other words: which are the interesting features people should learn when they go from a langauge such as Java or C# to a language like Python or Ruby. We used Ruby as the concrete example language.

We started the discussion about important features with the concept of dynamically changing an object’s type and the idea of message passing. We then looked at the concepts of blocks and closures. Next in line is a discussion about functions that create functions as well as currying. This lead into a quick discussion about continuations. Open classes, aliasing and the relationship to AOP was next on our agenda.

We then looked considered a somewhat more engineering-oriented view and looked at the importance of testing and what are the best steps of getting from static programming to dynamic programming. Finally, we discussed a bit about the current (as of October 2006) state of dynamic languages on mainstream platforms.

Links:

• The Seaside web framework
• AspectR, AOP for Ruby
• IronPython, Python on .Net
• JRuby, Ruby on the JVM
• Jim Weirichs blog
• Niclas Nilsson’s blog
• Groovy

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Recording Venue:
Guest(s):
Host(s): Arno Eberhard
Recording Venue:
Guest(s):
Host(s): Arno Eberhard
In recent episodes we have discusses statically and dynamically typed languages and domain specific languages – topics that are much talked about in the community at the moment. In this episode we look at the foundation of programming languages : types. We explain what a type actually is, how type systems work and what polymorphism works.

Links:

• The well known On Understanding Types, Data Abstraction, and Polymorphism paper with an impressive number of citations.
• Definition of Type Systems at Wikipedia

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Recording Venue:
Guest(s): Thomas Quas
Host(s): Alexander
Ruby has been getting more and more attention by the developer community over the last couple of years. Nevertheless Ruby as language and as a plattform is not too widespread. Most developers don’t know people who have actually done commercial Ruby projects. Therefore it is sometimes hard to judge if Ruby is just a hype topic or if Ruby can be used for serious projects today. In this episode Alexander speaks with Thomas Quas about a commercial Ruby project Thomas finished a while ago. Thomas shares his insights and practical experiences with Ruby doing a project under strong time pressure. As Thomas has many years experience doing Java projects we also do some high level comparisons between both platforms.

Links:

• Ruby-GNOME2
• Scripting Windows Apps
• Duck Typing
• Ruby Mixins
• Pickaxe Book
• RubyCocoa – A Ruby/Objective-C Bridge for Mac OS X with Cocoa
• Some information on Ruby 2

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