ruby-freeze

# Ruby freeze

# Number
num = 1.freeze
num += 1              # No Error

# String
name = 'Tom'.freeze
name << ' Hardy'      # FrozenError

# Array
texts = ['a', 'b', ['c', 'd'], {e: 'f'}].freeze
texts[0] << 'b'       # No Error
texts[1].replace('c') # No Error
texts[2] << 'e'
texts[3].merge!({g: 'h'})
texts                 # => ["ab", "c", ["c", "d", "e"], {:e=>"f", :g=>"h"}]
texts[0] = 'b'        # FrozenError

hash = {a: 'b', c: 'd', e: ['f']}.freeze
hash[:a] << 'b'
hash[:c].replace('dd')
hash[:e] << 'g'
hash                  # => {:a=>"bb", :c=>"dd", :e=>["f", "g"]}
hash[:a] = 1          # FrozenError