Iterators

• Iterators make it easier to write code

5.times do
  puts “hello”
end

• Integers/floats: times, unto, down to, step
• Range: each, step
• String: each, each_line, each_byte
• Array: each, each_index, each_with_index
• Hash: each, each_key, each_value, each_pair

Methods

• Values are passed in when they are called, and they are sometimes abbreviated as args
• Operators are also methods in ruby
• Syntactic sugar refers to simplifying the code
• Syntactic vinegar – not so tasty code
• Methods are all lowercase with underscores

Classes

• Classes use camel case (they always start with a capital letter): SomeName
• Classes group the code into discreet, well-categorized areas
• Can define methods inside a class

class Animal
  def make_noise
    “Moo!”
  end
end

animal.make_noise
  returns “Moo!”

• make_noise object is created from the class and then we can tell it to do things
• Objects let us organize code into well-categorized areas
• Allow complex behaviors using simple statements
• Instance: an object created from a class

animal = Animal.new
puts animal.make_noice

• Animal.new is an instance which is an object
• .new is a class method

Instance Variables

• Instance variables start with an @ symbol – @variable
• Instance variables are used within the instance of a class
• Allow us to keep track of attributes
• Never have access to instance variables from outside the instant
• We can access methods within instance, so need to use methods to get instance variable
• Setter methods – sets a variable equal to value
• Getter methods – getting that value back

Attribute Methods

• Methods that we put into classes – takes symbols and turns them into methods
  • attr_reader
  • attr_writer
  • attr_accessor (creates a reader and a writer method)

Additional Terms

• Instantiated = creating a new instance
• Class Method – a method that can be called on a class even without an instance of the class
• Class attributes – store values that apply to the class generally stored in a class variable @@variable
• Instance variables are only inside the instance
• Inheritance – inherits the methods and attributes of another class
• Can only inherit from one super class
• Modules are wrappers around classes