+class Hash
+ def slice(*keep_keys)
+ h = {}
+ keep_keys.each { |key| h[key] = fetch(key) }
+ h
+ end unless Hash.method_defined?(:slice)
+
+ def except(*less_keys)
+ slice(*keys - less_keys)
+ end unless Hash.method_defined?(:except)
+
+ def deep_symbolize_keys
+ inject({}) { |result, (key, value)|
+ value = value.deep_symbolize_keys if value.is_a?(Hash)
+ result[(key.to_sym rescue key) || key] = value
+ result
+ }
+ end unless Hash.method_defined?(:deep_symbolize_keys)
+
+ # deep_merge_hash! by Stefan Rusterholz, see http://www.ruby-forum.com/topic/142809
+ MERGER = proc do |key, v1, v2|
+ Hash === v1 && Hash === v2 ? v1.merge(v2, &MERGER) : v2
+ end
+
+ def deep_merge!(data)
+ merge!(data, &MERGER)
+ end unless Hash.method_defined?(:deep_merge!)
+end
+