Why do I have access to an instance method attribute?

Question

ruby

I’m reading a book and already on the hundredth page I’m at an impasse I don’t understand why I can change the attribute of the instance method

class Dog
    attr_reader :name, :age
   def name=(value)
     if value == ""
       raise "Name can't be blank!"
     end
     @name = value
   end
   def age=(value)
    if value < 0
      raise "An age of #{value} isn't valid!"
    end
    @age = value
   end
   def move(destination)
      puts "#{@name} runs to the #{destination}."
   end
   def talk
     puts "#{@name} says Bark!"
   end
   def report_age
     puts "#{@name} is #{@age} years old."
   end
end
dog = Dog.new
dog.name = "Daisy"
dog.age = 3
dog.report_age
dog.talk
dog.move("bad")

how can I just set the Attribute in the move method because it is in the class
def move(destination)
with this line I just assign the attribute
dog.move("bad")
why can't I do it with name I 'm confused in
general help me figure it out ..
Not much is cleared up, but I can't understand why the first two methods are written like this

def name=(value)
     if value == ""
       raise "Name can't be blank!"
     end
     @name = value
   end
   def age=(value)
    if value < 0
      raise "An age of #{value} isn't valid!"
    end

def name=(value)
def age=(value)
And here is the
def move(destination)
method like this without equals =

Answer 1

attr_reader :name is not about setting read permissions. It's just a shorthand for declaring a method, all it does is declare a read method itself, analogous to

def name
  @name
end

attr_writer :name declares

def name=(value)
  @name = value
end

attr_accessor :name will declare both methods at once. move for you is already a method that works with internal data, it encapsulates them. Therefore it is declared as a method.
In fact, in ruby ​​all methods, in ruby ​​from the outside it is impossible to read the attribute without declared methods. move is similar to just a method familiar from other PLs. Its task is to hide the internal implementation of the class and provide an interface for working with it.