What is the difference between Methods and Attributes in Ruby?

Question

Can you give me an example?

Answer 1

Attributes are specific properties of an object. Methods are capabilities of an object.

In Ruby all instance variables (attributes) are private by default. It means you don't have access to them outside the scope of the instance itself. The only way to access the attribute is using an accessor method.

class Foo
  def initialize(color)
    @color = color
  end
end

class Bar
  def initialize(color)
    @color = color
  end

  def color
    @color
  end
end

class Baz
  def initialize(color)
    @color = color
  end

  def color
    @color
  end

  def color=(value)
    @color = value
  end
end

f = Foo.new("red")
f.color # NoMethodError: undefined method ‘color’

b = Bar.new("red")
b.color # => "red"
b.color = "yellow" # NoMethodError: undefined method `color=' 

z = Baz.new("red")
z.color # => "red"
z.color = "yellow"
z.color # => "yellow"

Because this is a really commmon behavior, Ruby provides some convenient method to define accessor methods: attr_accessor, attr_writer and attr_reader.