Journal of Research in Innovative Teaching - National University

considers a programming language as a user interface for programmers, so he designed Ruby “to
make programmers happy.” He based his design for Ruby on three main principles: conciseness,
consistency, and flexibility (Matsumoto, 2000).
These three principles make programming in Ruby not only fun but, more importantly,
productive. This is where Ruby stands out to be the language of choice in agile problem-driven
teaching environments. The principle of conciseness dictates that a language should do a lot of
work quickly. The principle of consistency means that a programmer with basic knowledge can
learn Ruby very quickly. Last but not least, the principle of flexibility means that Ruby will help
express humans, not restrict them. A Ruby programmer can write arbitrary objects that are
treated just like the built-in ones (Matsumoto, 2000).
Ruby Genealogy
Ruby is generally described as an object-oriented scripting language. This general description
relates directly to the genealogy of Ruby. Programming languages genealogy reveals how Ruby
was directly affected by several object-oriented and scripting languages, as shown in Figure 1
(Lévénez, 2009). Matz designed Ruby with the goal of having the right balance of functional and
imperative programming (About Ruby, 2009). Ruby inherited powerful data abstraction features
from Clu. It is as much dynamic and object-oriented as SmallTalk, Common Lisp, Eiffel, and
Clos. Ruby is as versatile as Perl and as powerful as Python (Scott, 2006).
Figure 1. Ruby Inherited Features from Different Programming Paradigms
Key Ruby Features
Ruby is purely object-oriented and is an interpreted language. These two characteristics put
every feature of the language in perspective according to the principles behind it. Ruby did not
introduce new features to the programming languages world, however, it did combine the best
available features from existing paradigms. These features are the reason Ruby stands out and
was chosen in this use case of agile teaching and learning.
Six-Level Scoping
Ruby has a spectacular six-level variable scoping system. This allows for flexible scoping and
the ability to encapsulate variables at different levels. A variable can be of global, local, class,
class instance, instance, or block scope. Each scope level is identified by a certain prefix or
naming convention. There are no variable declarations in Ruby. This made the course project
implementation easier, as there is no need to worry about variable types and declarations.
However, one would argue that this could cause issues due to ambiguity about variables. In fact,
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