"Immutable" objects (PORO VS u-attributes)

01.rb

require 'bundler/inline'

gemfile do
  source 'https://rubygems.org'
  gem 'u-attributes', '~> 2.6.0'
end

# -------------------  -------------------

class Person
  include Micro::Attributes.with(:initialize, :accept)
  
  attribute :name, default: -> value { String(value).strip },
                   reject: :empty?,
                   freeze: true

  def greet
    "Hi my name is #{name}!" if accepted_attributes?
  end
end

# -------------------  -------------------

person1 = Person.new(name: 'Rodrigo')
puts person1.greet

person2 = person1.with_attribute(:name, '')
puts person2.greet

person3 = person1.with_attribute(:name, 'Serradura')
puts person3.greet

p [person1, person2, person3].map(&:name)

02.rb

class Person
  attr_reader :name

  def initialize(name: nil)
    @errors = []

    @name = String(name).strip.freeze

    @errors << 'name must be filled' if @name.empty?
  end

  def valid?
    @errors.empty?
  end

  def greet
    "Hi my name is #{name}!" if valid?
  end

  def with_name(value)
    self.class.new(name: value)
  end
end

# -------------------  -------------------

person1 = Person.new(name: 'Rodrigo')
puts person1.greet

person2 = person1.with_name('')
puts person2.greet

person3 = person1.with_name('Serradura')
puts person3.greet

p [person1, person2, person3].map(&:name)