[Using getters / setters / class variables in Ruby]

getter_vs_setter.rb

class MyClass
  attr_reader :my_var

  def initialize
    @my_var = "initial value"
  end

  def demonstrate
    # IMPORTANT: `self` is OPTIONAL for getters but MANDATORY for setters
    puts "1. Reading with 'my_var': #{my_var}" # Calls the getter
    puts "2. Reading with 'self.my_var': #{self.my_var}" # Also calls the getter

    # This creates a NEW local variable, it does NOT change @my_var
    my_var = "local variable value"
    
    puts "3. The local variable is now: #{my_var}"
    puts "4. The instance variable is still: #{@my_var}" # Unchanged!
  end
end

instance = MyClass.new
instance.demonstrate

# OUTPUT
# 1. Reading with 'my_var': initial value
# 2. Reading with 'self.my_var': initial value
# 3. The local variable is now: local variable value
# 4. The instance variable is still: initial value