Ruby basics workshop #1

README.md

Ruby workshop agenda

1. Data types
2. Basic syntax
3. Objects, data types/structures (basic)
4. Ecosystem – gems, docs; C extensions
5. Blocks & loops

Advanced:

• parallel assignment
• blocks & procs & lambdas
• classes, modules, inheritance
• threads & GVL

Tips for learning

• reading code
• writing code

basic_syntax.rb

foo = 42
bar = "baz"

class Fixnum
  def +(other)
    if other == 4
      100
    elsif other == 5
      50
    end

    case other
    when 4 then 7100
    when 5 then 750
    else 71
    end
  end
end

# receiver.method_name(param, param2, param3)
# puts bar.size()
puts "weirdness\n", 4.+(4).inspect, (3 + 3).inspect

blocks.rb

# def trice
#   yield
#   yield
#   yield
# end

# trice { puts 'first' }

# puts '=' * 20

# trice do
#   puts 'second'
# end

# trice {}

def calculate
  yield :info, "Starting..."
  # oooo....
  if rand(10) < 4
    yield :error, "Failed with an error!"
  else
    yield :info, "Success."
  end
  yield(:info, "Finished.")
end

require 'logger'
logger = Logger.new(STDOUT)

calculate do |severity, message|
  # logger.public_send(severity, message)
  case severity
  when :info  then logger.info(message)
  when :error then logger.error(message)
  end
end

calculate {}

# ---------------

def apply_taxes(amount)
  amount + yield(amount)
end

puts apply_taxes(100) { |amount| amount * 0.2 }

built_in_loops.rb

x = [1, 2, 5, 12, 'baba']

# Enumerable
result = x.each { |item| puts "item: #{item}" }
puts "=> #{result.inspect}"

result = x.map { |item| item * 2 }
puts "=> #{result.inspect}"

makeshift_loops.rb

x = [1, 2, 5, 12, 'baba']

def iterate_over(enumerable)
  length = enumerable.length
  i = 0

  while i < length
    current_item = enumerable[i]
    i = i + 1

    yield current_item
  end
end

def transform(enumerable)
  length = enumerable.length
  i = 0
  result = []

  while i < length
    current_item = enumerable[i]
    i = i + 1

    result << yield(current_item)
  end

  result
end

transformed = transform(x) do |item|
  # puts item
  item * item if item.is_a? Fixnum
end

puts transformed.inspect

objects.rb

# scope gates: def, class, module
class InfraTeam
  foo = 42

  def awesome(name = 'BBB')
    puts "Hello #{name}!"
  end

  def InfraTeam.awesome
    puts 'We are awesome!'
  end

  def self.awesome2
    InfraTeam.awesome
  end

  class << self
    def awesome3
      awesome
    end
  end
end

# InfraTeam.send(:private, :awesome)

name = "Bam" * 2
name.upcase!

InfraTeam.new.awesome
InfraTeam.awesome
InfraTeam.awesome2
InfraTeam.awesome3