Ruby

Quick History

Name chosen because it was the birthstone of the colleage of the creator Yukihiro Matsumoto

First public release Dec 21 1995

Created because Matsumoto wanted“ scripting language that was more powerful than Perl, and more object-oriented than Python."

Ruby is a pure OOP language everything is an object.

Anything and everything can be overloaded

5.times { print "We *love* Ruby -- it's outrageous!" }

Abstract Data Types

Again everything in ruby is an object Integers, booleans, and etc are objects and can

be modified and used as such e.x. int.to_i => int

int.to_int => int

int.floor => int

int.ceil => int

So to create an abstract data type, define a class and then generate an object

Ruby ADT ExampleClass Person_ADT def to_Person(parameter(s)) ...code... end def make(person1, person2) ...code... @person3 = person1 + person2 ...code... end def terminate_Person(person) puts "I'll be back!" endend

Ruby Inheritance

Ruby supports single inheritance, meaning it can only inherit properties from a single class

By default methods are public, though java-like private and protected methods can be defined using the private and protected keywords respectively

Subclass methods can override superclass methods using the def

Ruby Inheritance Examplesclass Bird def preen puts "I am cleaning my feathers." end def fly puts "I am flying." end end class Penguin < Bird def fly puts "Sorry. I'd rather swim." end end p = Penguin.new p.preen p.fly

Ruby Dynamic Binding

Because Ruby allows for the overriding of methods some mechanism is needed to determine which method is being called when multiple methods with the same name exist

Ruby makes use of dynamic dispatching. The calling object is what determines which method is implemented.

In the previous example the method fly() is defined twice and executes differently if a Bird or Penguin object is the calling method

Ruby Subclasses

Once more, everything is an object in Ruby, so rather than having subtypes for subclasses, Ruby just has subclasses that are an extension of the parent object

Also Ruby allows nested classes, you can define classes within other classes. A good example of this is inherited classes in Ruby.

Nested Classes

Ruby allows

Ruby Nested Classes Example

class A < Object

def initialize

@y = 0

end

class B < Object

def initialize

@x = 0

end

def f

# ...

end

end

end