BRUG MAY 2019 - Code Examples

code_example.rb

# example for send

'brug'.split('')
'brug'.class.ancestors

# ====================================================

# LEVEL 0

class Employee

  def name
    'Hi! I am a Employee.'
  end

  private

  def hello
    'Say Hola!'
  end
end

# ====================================================
# LEVEL 1

# Method missing example

class Account
  attr_accessor :state

  def initialize(state)
    @state = state
  end

  def method_missing(method_name, *args, **keyword_args, &block)
    if result = method_name.match(%r(\Adebit_\d*\z))
      self.state = state - extract_number(result)
    elsif result = method_name.match(%r(\Acredit_\d*\z))
      self.state = state + extract_number(result)
    else
      super
    end
  end

  private

  def extract_number(matched_result)
    matched_result[0].split('_')[1].to_i
  end
end

account = Account.new(20000)
account.debit_200
account.state
account.credit_999
account.state

# ========================================================


# LEVEL 2
# Ruby Method Precedence example

module Developer
  def name
    puts "Hi. This is Developer"
  end
end

class Employee
  def name
    puts "Hi. This is Employee"
  end
end

class Analyst < Employee
  include Developer

  def name
    puts "Hi. This is Analyst"
  end
end

analyst = Analyst.new
analyst.name


# ========================================================
# LEVEL 3
# Ruby Method Precedence example

module Developer
  def name
    puts "Hi. This is Developer"
  end
end

module Analyst
  def name
    puts "Hi. This is Analyst"
  end
end

class Employee
  include Developer

  def name
    puts "Hi. This is Employee"
  end
end


e = Employee.new
e.extend(Analyst)
e.name

# ========================================================
# LEVEL 4
# Ruby Method Precedence example

module Developer
  def name
    puts "Hi. This is Developer"
  end
end

module Analyst
  def name
    puts "Hi. This is Analyst"
  end
end

class Employee
  include Analyst
  prepend Developer

  def name
    puts "Hi. This is Employee"
  end
end


e = Employee.new
e.name

# ========================================================


# LEVEL 5
# Ruby Method Precedence example

module Reviewer
  def name
    puts "Hi. This is Reviewer"
    super rescue nil
  end
end


module Manager
  def name
    puts "Hi. This is Manager"
    super rescue nil
  end
end

module Analyst
  def name
    puts "Hi. This is Analyst"
    super rescue nil
  end
end

class Employee

  # inherited method to class Employee
  def name
    puts "Hi. This is Employee "
    super rescue nil
  end
end

class Developer < Employee
  include Reviewer # including method into class Employee
  prepend Analyst # prepending method to class Employee

  # instance method to class Employee
  def name
    puts "Hi. This is Developer"
    super rescue nil
  end
end

developer_1 = Developer.new


def developer_1.name
  puts "Hi. This is developer_1"
  super
end

developer_1.extend(Manager)
developer_1.name


# ========================================================

# DSL Example

FactoryGirl.define do
  sequence :github_username do |n|
    "github_#{n}"
  end

  factory :user do
    description "Learn all about Git"
    github_username

    trait :admin do
      admin true
    end
  end
end


# ========================================================
# DSL Example

SearchFlight.origin('BLR').destination('DEL').depart('2019-05-31').return('2019-06-10')


# ========================================================

# define method example

class Doctor
  ["rhinoplasty", "checkup", "interpretive_dance"].each do |action|
    define_method("perform_#{action}") do |argument|
      "performing #{action.gsub('_', ' ')} on #{argument}"
    end
  end
end

doctor = Doctor.new
puts doctor.perform_rhinoplasty("nose")
puts doctor.perform_checkup("throat")
puts doctor.perform_interpretive_dance("in da club")



# ========================================================

# define method

class Emoji

  def initialize
    emoji_lists = {
      grinning_face: "&#128512",
      grinning_face_with_smiling_eyes: "&#128513",
      face_with_tears_of_joy: "&#128514",
      rofl: "&#129315",
      smiling_face_with_open_mouth: "&#128515",
      smiling_face_and_smiling_eyes: "&#128516",
      smiling_face_and_cold_sweat: "&#128517"
    }

    emoji_lists.each do |key, value|
      self.class.send(:define_method, "#{key}") do
        value
      end
    end
  end
end

# ========================================================

# class_eval example

class Employee
end

# Employee is evaluated as a class

Employee.class_eval do
  def say_hello
    puts 'Hello'
  end
end

e = Employee.new
e.say_hello
=> Hello


# String is evaluated as a class

'brug'.class.class_eval do
  def split_by_word
    split(' ')
  end
end

'Srinidhi is presenting'.split_by_word
=> ["Srinidhi", "is", "presenting"]


# ========================================================

# instance_eval example

class Mentor
end

teacher = Mentor.new
teacher_1 = Mentor.new

# teacher is evaluated as a instance

teacher.instance_eval do
  def evaluate
    puts 'Yes I evaluate'
  end
end

teacher.evaluate
=> Yes I evaluate

teacher_1.evaluate
NoMethodError: undefined method `evaluate' for #