#
# Hello world of Ruby objects!
puts "Hello, World!"
# >> Hello, World!
puts "Hello, World!".reverse
# >> !dlroW ,olleH



#
#numbers
puts 3 + 4 
puts 3.14 * 7
puts 1.01 + 1.99 
# >> 7
# >> 21.98
# >> 3.0



#
#ranges
range = 1..5
puts range
puts range.class 

range = 1..5
range.each { |x| puts x * 2 }
puts (1..5).collect { |x|  x * 2 } # !> (...) interpreted as grouped expression
# >> 2
# >> 4
# >> 6
# >> 8
# >> 10
# >> 2
# >> 4
# >> 6
# >> 8
# >> 10





#
#regex 
re = /(\w+) (\w+)/ 
re =~ "howdy doody"
puts "#{$2} #{$1}"
# >> doody howdy

a = "Matt"
b = "Hello, #{a}, how are you today?"
puts b
# >> Hello, Matt, how are you today?


#
# Everything is an Object
#

puts 3.class
# >> Fixnum

puts 3.times { puts "Hello, World!" }
# >> Hello, World!
# >> Hello, World!
# >> Hello, World!
# >> 3


number = 5
number.times {|x| puts x }
# >> 0
# >> 1
# >> 2
# >> 3
# >> 4









#
# classes and a little duck typing
class Vehicle
  def blare  
    horn.upcase
  end
end

v = Vehicle.new
puts v.blare

class Car < Vehicle
  def horn
    "beep!"
  end
end

class Truck < Vehicle
  def horn
    "honk!"
  end
end


c = Car.new
puts c.horn

t = Truck.new
puts t.horn

puts c.blare
# >> beep!
# >> honk!
# >> BEEP!





#
# Accessors
class Book
  attr_accessor :title
  attr_writer :author
  attr_reader :author
end

book = Book.new
book.title = "Programming Ruby"
book.author = "Dave Thomas, Andy Hunt"

puts "\"#{book.title}\" by #{book.author}"
# >> "Programming Ruby" by Dave Thomas, Andy Hunt



#
# Scoping
$GV = "Global Variable"
$gv = "global variable.... very bad!"
class MyObject
  Constant = "constant"
  @instance_variable = "instance_var"
  @@class_variable = "class_var"

  def method
    local_variable = ""
  end
end



#
# Mixins
class Object 
  def hello
    to_s
  end
end

a = "abcdefg"
puts a.class
puts a.hello
puts 3.hello
# >> String
# >> abcdefg
# >> 3


#
# Super open
class Hello
  def method_missing(method, *args, &block)
    puts "creating '#{method}' method..."
    self.class.send(:define_method, method, &eval("proc{puts \"hello #{method}\"}"))
    send(method)
  end
end

hello = Hello.new
hello.bob
hello.george
hello.bob

hello2 = Hello.new
hello2.bob
# >> creating 'bob' method...
# >> hello bob
# >> creating 'george' method...
# >> hello george
# >> hello bob
# >> hello bob




#
# Least Astonishment
#

#
# arrays
arr = [1,2,3,"four",5]
arr.each { |x| puts x }
puts arr.join(",")
puts arr.reverse.join(",")
# >> 1
# >> 2
# >> 3
# >> four
# >> 5
# >> 1,2,3,four,5
# >> 5,four,3,2,1

arr = [23,1,56,4,8,5,18,2]
puts arr.sort.reverse
# >> 56
# >> 23
# >> 18
# >> 8
# >> 5
# >> 4
# >> 2
# >> 1


#
# methods
def print_fib_to(max) 
  a = b = 1
  while a <= max
    puts a
    c = a + b
    a,b = b,c
  end
end
print_fib_to 13
# >> 1
# >> 1
# >> 2
# >> 3
# >> 5
# >> 8
# >> 13


# hashes
hash = { "a" => "apple", 
         "b" => "banana", 
         "c" => "cherry" }

hash.each {|key, value| puts "#{key} => #{value}"}
# >> a => apple
# >> b => banana
# >> c => cherry


#
# closures / blocks
hash = { "a" => "apple", "b" => "banana", "c" => "cherry" }

def do_something_with_hash(hash, array, &something)
  array.each do |key|
    something.call hash[key]
  end
end

do_something_with_hash(hash, ["a","c"]) { |x| puts "#{x} pies" }
# >> apple pies
# >> cherry pies


#
# hashes as parameter catch-alls
def myMethod(name, params) 
  puts name
  params.each { |key, value| puts "#{key} => #{value}" }
end

myMethod "my favorite song", 
          "title" => "Red House", 
          "artist" => "Jimi Hendrix", 
          "album" => "Are You Experienced?", 
          "year" => 1970
# >> my favorite song
# >> artist => Jimi Hendrix
# >> title => Red House
# >> year => 1970
# >> album => Are You Experienced?


#
# Symbols
sym = :may
puts sym
puts sym.class
# >> may
# >> Symbol


hash = {:apple => "apple", :banana => "banana", :cherry => "cherry"}
puts hash[:apple]
# >> apple