初歩的かもしれないが躓いたのでメモ class Person attr_accessor :name def initialize(name) @name = name end end john = Person.new("John") john.freeze (john.name = "Tony") rescue p $! #=> #<RuntimeError: can't modify frozen Person> str = String.new("Hello!") str.freeze str = "Hi!" st</runtimeerror:>…