1. CSE4102/5102 Team Project Ruby & Ruby on Rails
Savanna Smith, Samantha Gustafson

2. Motivation Ruby provides … Readability
Helpful conventions for ease in development.
Exemplifies language paradigms
Flexibility
Users can add their own methods to Ruby’s base code so it runs in a way that is specific to their needs.

3. Biography - Yukihiro Matsumoto
Self taught programmer
Information science degree from University of Tsukuba in Japan
Worked at netlab.jp when he came up with the idea for a powerful scripting language that was also object-oriented (aka Ruby)
He currently works at Heroku
as Chief Architect of Ruby and
Technical advisor at VASILY, Inc.
took out other slides because it seemed like acknow and trivia were only for long ppt.

4. Biography - David Heinemeier Hansson
Danish programmer and founder of Ruby on Rails
Business administration and computer science degree from Copenhagen Business School
Hansson created a web-based project tool for Basecamp (previously 37signals)
Used Ruby to develop a unique
framework for this project, which
he later released in 2004 as Ruby
on Rails

5. History of Ruby 1993 simple, portable, object-oriented.
iterators and closures
exception handling and garbage collection.
2003, version 1.8
duck-typing
fully-qualified names,
UNIX commands, and many other features.
2007 Mac OS X ships with Ruby
2008, version 1.8.7
Ruby was at its peak.
Today, version 2.5.0

6. History of Ruby on Rails
2004
Released as an open source project.
2007
Apple shipped out Mac OS X with Rails included.
2009, version 2.3
New developments in engines, templates, Rack and nested model forms.
2008
Web app framework Merb was released.
Rails to include best parts of Merb in Rails 3.0.
Today, version 5.1
Included JavaScript.

7. Language Paradigm Primarily object-oriented
encapsulation, polymorphism, inheritance, and classes
But Ruby also supports imperative, functional, and reflective paradigms
Allows users to code in whatever style they prefer, instead of forcing them to adapt to one style

8. Functional Programming
Higher-order function: takes a function or returns one.
First-class function support: When a language can handle those actions.
Functional programming requires that no states are changed when a function is run — we simply use the output of those functions.
Side effects: anything a function does to the rest of the program besides taking input and returning output.
Referential transparency: The ability to replace a function call with its resulting value.
Function composition: Combining two or more functions at once.
terms

9. Repositories/Libraries
Packet manager is RubyGems
A “gem” is a package that can be installed from the command line
Most gems are libraries, but there are a few that are applications
Over 9000 gems available on RubyGems.org

10. IDEs RadRails (from Aptana) is a rapid application development IDE
It provides developers everything they need to design, test and execute their applications
RadRails was built on the Eclipse RCP, meaning RadRails tools are also available as Eclipse plug-ins.

11. IDEs
RubyMine (from JetBrains) provides coding assistance, code refactoring, and code analysis capabilities
It has built-in consoles, automatic Ruby Gems management and Rake support

12. Ruby Syntax Everything is an object in Ruby
Syntax is similar to others we’ve learned,
+, -, *, /
= is assignment operator
== is comparator operator
=== case equality
Comments are denoted as ‘#’

13. Ruby STDIN/STDOUT print: prints to screen
puts: also prints but followed by a new line
gets: first checks ARGV, then checks STDIN
STDIN.gets: takes input only from STDIN
print “hello world”
print “goodbye”
puts “hello world”
puts “goodbye”
puts “enter value:”
val = gets
puts val
hello worldgoodbye
hello world
goodbye
enter value: 14

14. Ruby File I/O File.new : creates file File.open : opens file
fp = File.new(“filename”, “mode”) # ... process the file fp.close
File.open : opens file
File.open(“filename”, “mode”)
Common modes:
“r” : read
“w” : write
File.rename : renames file File.rename(“oldname.txt” “newname.txt”)
fp.write( ) : writes to file fp.write(“word count”)

15. Variables (cont.) local variable var instance variable @var
class variable
global variable
$var
constant (begins with uppercase letters)
VAR

16. Methods Definitions Simple method definition (ex. line 1)
Method with argument (ex. line 5)
Method with multiple arguments (ex. line 9).

17. Method Return Methods return one object (ex. line 1)
They return the value of the last evaluated statement
Can also use “return” statements (ex. line 5)
Can get around the lack of multiple returns
For example, the method starting on line 12 actually returns the array: [1, “this is a multiple return!”]

18. Control Flow Conditional statements if, elsif, else, case, unless
Unconditional Loops
loop, break, next

19. Control Flow (cont.) Conditional Loops while, until
Looping over list of values
for, in
Iterators

20. Classes Can add methods to a class and create a constructor
To create a new class object, call “.new”
Example:

21. Classes (cont.) Instance Methods vs. Class Methods
Use instance methods on a particular instance of the class
Use class methods when a functionality belongs to that class and not to any one instance.
Example:

22. Classes - Inheritance
Inheritance is a key organizational technique for Rails
No multiple inheritance

23. Introspection and Reflection
self keyword: references the current object.
Introspection: examine an object’s type at runtime.
Reflection: examine and modify the structure and behavior of a program at runtime.
invoke a method on an object, instantiate a new object, modify an attribute of an object, all without knowing the names of the interfaces, fields, methods at compile time.

24. Modules Modules allow grouping methods, classes, and constants
provide a namespace
prevent name clashes
implement the mixin facility which eliminates the need for multiple inheritance
Example:

25. Functional Programming (cont.)
Lambdas allow us to store a function inside of a variable.
A Proc is a block — a series of commands that can be executed
Lambdas and Procs return to the method from which they were called. Procs are blocks and not methods so they will end the entire process they are inside.

26. Rails First you have to set up “behind the scenes” structures
skeleton of application, web server, database, etc.
> rails new library > Rails server
> create database db_name
In file ending in “.html.erb” you can format the look using some HTML practices
<h1> this is a header </h1>
<p> this is text on the page </p>
Rails provides a standard structure for web apps, so common patterns are done for you
Rails is succinct which leads to productive development

27. Word Frequency Code (FileIO)
total_count = 0
WORDS_COUNT = {}
File.readlines("platest1.txt").each do |line|
words = line.downcase.split
words.each do |word|
word = word.gsub(/[,.()'"]/,'')
if WORDS_COUNT[word]
WORDS_COUNT[word] += 1
else
WORDS_COUNT[word] = 1
end
fp = File.open('output.txt','w')
WORDS_COUNT.each do |key,value|
total_count+=value
fp.write("#{key} = #{value}\n")
fp.write("total count = #{total_count}")
fp.close
output.txt:
cse4102 = 1 programming = 2
language = 2 assignments = 1 pla = 1 due = 5 dates = 1
...
new_u_words_min = 1 these = 1 have = 1 added = 1 shown = 1 below = 1 number = 1 last = 1 total count = 624
repl.it/PresentationRubyExample

28. Word Frequency Code (stdin/stdout)
total_count = 0
WORDS_COUNT = {}
$/ = "ENDS"
print "enter text: "
line = STDIN.gets
words = line.downcase.split
words.each do |word|
word = word.gsub(/[,.()'"]/,'')
if WORDS_COUNT[word]
WORDS_COUNT[word] += 1
else
WORDS_COUNT[word] = 1
end
WORDS_COUNT.each do |key,value|
total_count+=value
puts "#{key} = #{value}"
puts "total count = #{total_count}"
cse4102 = 1 programming = 2
language = 2 assignments = 1 pla = 1 due = 5 dates = 1
...
these = 1 have = 1 added = 1 shown = 1 below = 1 number = 1 last = 1 ends = 1 total count = 625
repl.it/PresentationRubyExample

29. Conclusion
Ruby and Ruby on Rails is great to learn, especially for its ease of use and object-oriented and functional paradigms.
Sites created with Rails
Airbnb
Github
Bloomberg
and more!
Hulu
Twitch
Urban Dictionary