Classes in ruby are first-class objects. Each is an instance of class Class
A class can be defined simply as:
class House
end
Classes 🔗
To make an instance of House
house_1 = House.new
We can set values to the House class, which will be inherited by every instance.
class House
def initialize(color)
@color = color
end
end
house = House.new('blue')
We can access the instance values by creating getter methods in the class.
class House
def initialize(color)
@color = color
end
def color
@color
end
end
house = House.new('blue')
puts house.color
We can also set new values to instances by creating setter methods in the class.
class House
def initialize(color)
@color = color
end
def color
@color
end
def color=(new_color)
@color = new_color
end
end
house = House.new('blue')
puts house.color
house.color = "red"
puts house.color
A better way to create the getter and setter without having to create new methods is to use attr_reader and attr_writer
class House
attr_reader :color
attr_writer :color
def initialize(color)
@color = color
end
end
house = House.new('blue')
puts house.color
house.color = "red"
puts house.color
An even better way is to use attr_accessor to read and write
class House
attr_accessor :color
def initialize(color)
@color = color
end
end
house = House.new('blue')
puts house.color
house.color = "red"
puts house.color
A parent class can have its own variable, and they are denoted with two @@
class House
@@count = 0
def initialize(color)
@color = color
end
end
house = House.new('blue')
We can create a getter method for a parent class by using the self.[method name]
class House
@@count = 0
def self.count
@@count
end
def initialize(color)
@color = color
@@count += 1
end
end
house = House.new('blue')
puts house.count
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