Ruby/String/freeze

greet = "Hello, myValue!"
greet.freeze
greet.concat("!") # => TypeError: can"t modify frozen string

greet = "Hello, myValue!"
greet.freeze

greet = "Hello, myValue!"
greet.frozen? # => true

greet = "Hello, myValue!"
greet.freeze
# try to append something
greet.concat("!") # => TypeError: can"t modify frozen string
# is the object frozen?
greet.frozen? # => true

str = "This is a test. "
str.freeze
begin
  str << " Don"t be alarmed."   # Attempting to modify
rescue => err
  puts "#{err.class} #{err}"
end
# Output:
#   TypeError: can"t modify frozen string