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require 'hashery/crud_hash'
module Hashery
# The KeyHash class is a Hash class which accepts a block for
# normalizing keys.
#
# The KeyHash class is essentially the same as a normal Hash.
# But notice the significant distinction of indifferent key
# access.
#
# s = KeyHash.new
# s[:x] = 1
# s[:x] #=> 1
# s['x'] #=> 1
#
# We can see that internally the key has indeed been converted
# to a String.
#
# s.to_h #=> {'x'=>1 }
#
# By default all keys are converted to strings. This has two advantages
# over a regular Hash is many usecases. First it means hash entries have
# indifferent access. <tt>1</tt>, <tt>"1"</tt> and <tt>:1</tt> are all
# equivalent --any object that defines <tt>#to_s</tt> can be used as a key.
# Secondly, since strings are garbage collected so will default KeyHash
# objects.
#
# But keys can be normalized by any function. Theses functions can be quite
# unique.
#
# h = KeyHash.new(0){ |k| k.to_i }
# h[1.34] += 1
# h[1.20] += 1
# h[1.00] += 1
# h #=> { 1 => 3 }
#
class KeyHash < CRUDHash
#
# Unlike a regular Hash, a KeyHash's block sets the `key_proc` rather
# than the `default_proc`.
#
def initialize(*default, &block)
super(*default)
@key_proc = block || Proc.new{ |k| k.to_s }
end
end
end
#class Hash
# #
# # Convert a Hash to a KeyHash object.
# #
# def to_keyhash
# Hashery::KeyHash[self]
# end
#end
Version data entries
7 entries across 6 versions & 2 rubygems