The document provides an overview of Ruby programming concepts and syntax, including object-oriented features, dynamic typing, and various methods. It showcases code examples demonstrating array manipulation, method definitions, and the use of blocks, along with basic testing using the Test::Unit framework. Additionally, it mentions the Ruby standard library and gems for enhancing productivity.

2. puts “Hello Ruby!”

3. Clean, Elegant
and
Meaningful Syntax

4. test_string = 'string for test'
puts 'matched' if test_string.match 'string'
files = Dir['*.txt']
for file in files
file_ref = open file
file_ref.each_line { |line| puts line.reverse.upcase }
end

5. Everything is an Object
10.times { puts “Hello World!” } “Hello World!”.methods

6. Dynamic Typing,
Duck Typing
and
Open Classes

7. a_variable = 'a b c'.split(' ') #=> ['a','b','c']
a_variable = a_variable.join(' ') #=> 'a b c'
def a_function object_par
puts object_par.crazy_method
end
a_function [1,2,3] #=> error: undefined method 'crazy_method' for class Array
class Array
def crazy_method
return 'crazy method for an array'
end
end
a_function [1,2,3] #=> puts 'crazy method for an array'

8. a_variable = 'a b c'.split(' ') #=> ['a','b','c']
a_variable = a_variable.join(' ') #=> 'a b c'
def a_function object_par
puts object_par.crazy_method
end
a_function [1,2,3] #=> error: undefined method 'crazy_method' for class Array
class Array
def crazy_method
return 'crazy method for an array'
end
end
a_function [1,2,3] #=> puts 'crazy method for an array'

9. def a_function object_par
puts object_par.crazy_method
end
some_obj = SomeClass.new
a_function some_obj #=> error: undefined method 'crazy_method' for class SomeClass
def some_obj.crazy_method
return 'this is a crazy feature'
end
a_function some_obj #=> puts 'this is a crazy_feature'

10. def a_function object_par
puts object_par.crazy_method
end
some_obj = SomeClass.new
a_function some_obj #=> error: undefined method 'crazy_method' for class SomeClass
def some_obj.crazy_method
return 'this is a crazy feature'
end
a_function some_obj #=> puts 'this is a crazy_feature'

11. "if it walks like a duck and quacks like a
duck, then it is a duck”

12. Blocks

13. def square an_array
return an_array.map { |e| e*e }
end
lines_of_a_doc.each_with_index do |line,i|
if i.even? then
puts 'even line: #{line}'
else
puts 'odd line: ' + line
end
end

14. [1,2,3,4].select { |e| e.even? }
#=> [2,4]
[1,2,3,4].collect { |e| e.even? }
#=> [true,false,true,false]
[1,2,3,4].inject(0) { |sum,e| sum += e }
#=> 10

15. def my_for n
n.times { |n| yield(n) }
end
my_for 3 { |i| puts i }
#=> 1
#=> 2
#=> 3

16. Mix-in

17. class Books < Collection
def initialize
@books = SomeReader.new('some_file_with_books').get_books
end
include Enumerable
def each
@books.each { |book| yield(book) }
end
end
Class Books now have
map, select, inject, grep, find_all, include?
and more

18. Testing

19. require 'test/unit'
class TestHtmlParser < Test::Unit::TestCase
must “find all imgs” do
parser = HtmlParser.new '<div class='a'> <br/> <img src='img1.jpg'>n
<p><img src='img2.jpg'></body>'
assert_equal parser.parse_imgs, ['img1.jpg','img2.jpg']
end
end
class HtmlParser
def initialize html_doc
@content = html_doc
end
def parse_imgs
@content.scan(/imgs+src='(.+?)'/)
end
end

20. Standard Library
● erb - .rhtml
● sockets
● threads
● html/xml parser
● ftp, http, imap, pop3, smtp
● tk
● pstore

21. And Gems!
$ gem install rails
$ gem install rspec
$ gem search twitter
13,007 gems and counting!

22. Productivity and fun
And that's it!
Duda Dornelles
dudassdornelles@gmail.com