Intro to Classes 2 checkpoint

_notes

1. Getter and setter methods can be used for accessing the attributes of a class, but you'll often want to create a new instance of a class with default attribute values. **Getter and setter methods can only access attributes after an instance of a class has been created**.  THIS IS HUGE!! REPEAT REPEAT REPEAT!!! Ruby has a standard method named initialize that is executed when you create a new class instance:

```code
class President
  attr_accessor :age

  def initialize(years)
    @age = years
  end
end
```

Now we are essentially creating an **interface** for our President class. We have allowed the age attribute to be set by a theoretical user, rather than "hard-coding" the value as we did in the prior example.

_output

``` Block output - initialize
```
Car initialize should take make, model and year

``` Block output - class methods
```
Car initialize should take make, model and year
 Car wheels should return a standard number of wheels for any car
 Car axels should return a standard number of axels for any car

_questions

1. What exactly is an interface?  This idea of creating a "prepackaged" class that's in a valid state reminds me of C# - when you write a "constructor."  I'm probably confusing things.  This is imp stuff - let's discuss :)

Intro to Classes 2 checkpoint

# INITIALIZE

class Car
  attr_accessor :make
  attr_accessor :model
  attr_accessor :year
  
  def initialize(make, model, year)
    @make, @model, @year = make, model, year
  end 
end

# Class methods

class Car 
  attr_accessor :make
  attr_accessor :model
  attr_accessor :year
  
  def initialize(make, model, year)
    @make, @model,@year = make, model, year
  end
  
  def self.wheels
    4
  end
  
  def self.axels
   2
  end
end