dynamic_instance_variables

💼 Dynamic Instance Variable Management

Use instance_variable_set, instance_variable_get, and remove_instance_variable to manage object state dynamically, especially when keys or attributes aren’t known at compile time. This technique is powerful for building DSLs or serializers that map arbitrary data into Ruby objects.

class Person
  def initialize(name)
    @name = name
  end

  def set_prop(key, value)
    instance_variable_set("@#{key}", value)
  end

  def get_prop(key)
    instance_variable_get("@#{key}")
  end

  def remove_prop(key)
    ivar = "@#{key}"
    remove_instance_variable(ivar) if instance_variable_defined?(ivar)
  end
end

person = Person.new("Alice")
person.set_prop(:age, 30)
p person.get_prop(:age)          # => 30
p person.instance_variables      # => [:@name, :@age]
person.remove_prop(:age)
p person.instance_variables      # => [:@name]