Class: Kodekopelli::FrozenKeyHash

Inherits:
Hash
  • Object
show all
Defined in:
lib/kodekopelli/frozen_key_hash.rb

Overview

A FrozenKeyHash differs from a normal Hash in that, once a value has been set for a particular key, subsequent attempts to assign values to the same key will be ignored.

Please note that it is still possible to replace existing keyed values by first calling delete on the relevant key and then adding the new value.

Instance Method Summary collapse

Constructor Details

#initialize ⇒ FrozenKeyHash

Returns a new, empty hash.

:call-seq:
  FrozenKeyHash.new -> frozen value hash



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# File 'lib/kodekopelli/frozen_key_hash.rb', line 15

def initialize
  super
end

Instance Method Details

#[]=(key, value) ⇒ Object

Element Assignment—Associates the value given by a value object with the key given by a key object, unless an object with the same key is already stored in the hash. In the event that an object is already stored in the hash using the key provided, the hash will not be altered.

:call-seq:
  h[ aKeyObject ] = aValueObject -> aValueObject



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# File 'lib/kodekopelli/frozen_key_hash.rb', line 29

def []=(key,value)
  self.store(key,value)
end

#store(key, value) ⇒ Object

Synonym for element assignment.

:call-seq:
  h.store( aKeyObject, aValueObject ) -> aValueObject



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# File 'lib/kodekopelli/frozen_key_hash.rb', line 38

def store(key,value)
  unless  has_key?(key)
    super(key,value)
  end
end

#store_all(any_hash) ⇒ Object

Convenience method to merge all entries from another hash into the current instance, while still preserving existing key immutability



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# File 'lib/kodekopelli/frozen_key_hash.rb', line 49

def store_all(any_hash)
  any_hash.each_pair { |key,value|
    self.store(key,value)
  }
end

#to_s ⇒ Object 



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# File 'lib/kodekopelli/frozen_key_hash.rb', line 55

def to_s
  human_readable = ''
  human_readable += sprintf("%-30s     %s", "<KEY>", "<VALUE>")
  human_readable += "\n"
  each_pair {|key,value|
    human_readable += sprintf("%-30s => %s", key, value)
    human_readable += "\n"
  }
  human_readable
end