A Brief Overview of Ruby

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

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