1. Ruby for Newbies
Andrew Grimm
University of New
South Wales

2. What is Ruby?
Multi-paradigm language
Object-oriented programming
Functional programming
Procedural programming

3. Just about everything is an Object
>> 42.is_a?(Object)
=> true
>> "hello world".is_a?(Object)
=> true
>> nil.is_a?(Object)
=> true
>> Object.is_a?(Object)
=> true
>> Class.is_a?(Object)
=> true

4. Just about all instructions are
methods
puts “hello world” is a call to the method `puts`
>> private_methods.grep(/puts/)
=> ["puts"]

5. Enumerations
(1..5).each {|x| puts x}
(1..5).map {|x| x * 2}
(1..5).find_all {|x| x.odd?}
(1..5).sort_by {|x| [x.odd?.to_s, x]}
(1..5).group_by {|x| x.odd?}

6. Ruby (kind of) does functional
programming
grouping_by = Proc.new {|x| x % 6 }
what_to_do = Proc.new {|x| p x}
numbers = 1..50
def group_by_and_process(numbers, grouping_by,
what_to_do)
what_to_do.call(numbers.group_by(&grouping_by))
end

7. Metaprogramming
plus = :+
number_1 = 12
number_2 = 30
number_1.send(plus, number_2) # => 42

8. You can do just about anything
old_stdout = STDOUT
STDOUT = StringIO.new
STDOUT.puts "this won't be printed"
STDOUT = old_stdout
STDOUT.puts "this will be printed"