cours

# Array + Hashes

a = [ 1, 'cat', 3.14 ] # array with three elements
puts "The first element is #{a[0]}"

a[2] = nil

puts "The array is now #{a.inspect}"

# -> The first element is 1
# -> The array is now [1, "cat", nil]



a = [ 'ant', 'bee', 'cat', 'dog', 'elk' ]
a[0] # => "ant"
a[3] # => "dog"
# this is the same:
a = %w{ ant bee cat dog elk }
a[0] # => "ant"
a[3] # => "dog"

inst_section = {
  'cello'     => 'string',
  'clarinet'  => 'woodwing',
  'violin'    => 'string',
  'drum'      => 'percussion'
}

:cello

inst_section = {
  cello:    'string',
  clarinet: 'woodwing',
  violin:   'string',
  drum:     'percussion'
}

inst_section[:cello]
inst_section[:drum]
inst_section[:violin]
inst_section[:tuba]

# Symbols

NORTH = 1
EAST  = 2
SOUTH = 3
WEST  = 4

walk(:north)
look(:east)



# If then else

if count > 10
  puts "Try again"
elsif tries == 3
  puts "You lose"
else
  puts "Enter a number"
end


while weight < 100 and num_pallets <= 30
  pallet = next_pallet()
  weight += pallet.weight
  num_pallets += 1
end


square = 2
while square < 1000
  square = square*square
end

# Regex
/P(erl|ython)/
/.+@.+\..+/


'Perl' =~ /P(erl|ython)/

'thibaut@milesrock.com' =~ /.+@.+\..+/

line.gsub(/Python/, 'Ruby')

# Blocks
{ puts "Hello" }

def call_block
  puts "Start of method"
  yield
  yield
  puts "End of method"
end

phone_numbers = ['0679389289', '078392982']

phone_numbers.each do |phone_number|
  if phone_number.index(1) == '6'
    call_number(phone_number)
  end
end

call_block { puts "In the block" }

def who_says_what
  yield("Dave", "hello")
  yield("Andy", "goodbye")
end

who_says_what { |a, b|
  puts "#{a} says #{b}"
}



animals = %w( ant bee cat dog elk )
animals.each {|animal| puts animal }

class Furniture
  attr_accessor :length, :height, :name, :weight
end

furniture = Furniture.new
furniture.length = 2



# Classes

class BookInStock
end


class BookInStock
  def initialize(isbn, price)
    @isbn = isbn
    @price = Float(price)
  end
end

class BookInStock
  def initialize(isbn, price)
    @isbn = isbn
    @price = Float(price)
  end
  def isbn
    return @isbn
  end
  def price
    @price
  end
end
book = BookInStock.new("isbn1", 12.34)
puts "ISBN = #{book.isbn}"
puts "Price = #{book.price}"

class BookInStock
  attr_reader :isbn, :price
  def initialize(isbn, price)
    @isbn = isbn
    @price = Float(price)
  end
end

book = BookInStock.new("isbn1", 12.34)
puts "ISBN = #{book.isbn}"
puts "Price = #{book.price}"

attr_reader :isbn, :price
attr_writer :isbn, :price
attr_accessor :isbn, :price

def price=(new_price)
  @price = new_price
end

book.price=(2)
book.price = 2

class BookInStock
  attr_reader :isbn
  attr_accessor :price
  def initialize(isbn, price)
    @isbn = isbn
    @price = Float(price)
  end
  def price_in_cents
    Integer(price*100 + 0.5)
  end
  def price_in_cents=(cents)
    @price = cents / 100.0
  end
end
book = BookInStock.new("isbn1", 33.80)
puts "Price = #{book.price}"
puts "Price in cents = #{book.price_in_cents}"
book.price_in_cents = 1234
puts "Price = #{book.price}"
puts "Price in cents = #{book.price_in_cents}"


-------------------
# public / private


# introspection
person = "Tim"
puts "The object in 'person' is a #{person.class}"
puts "The object has an id of #{person.object_id}"
puts "and a value of '#{person}'"


# Arrays
a = [ 3.14159, "pie", 99 ] a.class #=> Array a.length #=> 3
a[0] #=> 3.14159
a[1] #=> "pie"
a[2] #=> 99
a[3] #=> nil


a=[1,3,5,7,9]
a[1] = 'bat'
a[-3] = 'cat'
a[3] = [ 9, 8 ]
a[6] = 99
→ [1,3,5,7,9]
→ [1, "bat", 5, 7, 9]
→ [1, "bat", "cat", 7, 9]
→ [1, "bat", "cat", [9, 8], 9]
→ [1, "bat", "cat", [9, 8], 9, nil, 99]


# Files 
f = File.open("testfile") f.each do |line|
  puts "The line is: #{line}" end
f.close