Module: NamedArguments::HashExtendedTools

Defined in:
lib/named_arguments/hash_extended_tools.rb

Overview

Provides several hash utilities.

Note that you need to extend your hash with this module:

hash = {}
hash.extend HashExtendedTools
hash = hash.exclude :foo, :bar

Or create a new class:

class HashWithExtendedTools < Hash
  include HashExtendedTools
end

Instance Method Summary collapse

Instance Method Details

#attributes_as_hash(*attrs) ⇒ Object

Return the given attributes as a hash containing attribute => value pairs.

obj.a = 10
obj.b = 20
attributes_as_hash(:a, :b) 
  => {:a => 10, :b => 20}



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# File 'lib/named_arguments/hash_extended_tools.rb', line 75

def attributes_as_hash *attrs
  result = {}
  attrs.each do |a|
    v = self.send a
    result[a] = v unless v.nil?
  end
  result
end

#exclude(*keys_to_exclude) ⇒ Object

Return a new hash not including keys that are contained in keys_to_exclude.

Keys that match entries in keys_to_exclude are deleted if either they match as string or a symbol (created with to_sym).



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# File 'lib/named_arguments/hash_extended_tools.rb', line 44

def exclude *keys_to_exclude
  result = self.dup
  keys_to_exclude.each do |k|
    result.delete k.to_s
    result.delete k.to_sym
  end
  result
end

#slice(*slice_keys) ⇒ Object

Given an array of keys, return a hash containing the key/value pairs for the matching keys.

Values that are nil are not returned.



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# File 'lib/named_arguments/hash_extended_tools.rb', line 60

def slice *slice_keys
  result = {}
  slice_keys.each do |k|
    result[k] = self[k] unless self[k].nil?
  end
  result
end

#switch_keys(args = {}) ⇒ Object

Change keys in a hash.

Pass in a hash of:

old_key => new_key

Any keys matching old_key will be deleted and a new entry created with the same value and the new key.



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# File 'lib/named_arguments/hash_extended_tools.rb', line 25

def switch_keys args = {}
  args.each_pair do
    |old_key, new_key|
    if self.has_key?(old_key)
      self[new_key] = self[old_key]
      delete(old_key)
    end
  end
  self
end

#symbol_keys_as_strings ⇒ Object 



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# File 'lib/named_arguments/hash_extended_tools.rb', line 84

def symbol_keys_as_strings
  sym_keys = self.keys.select {|k| k.kind_of? Symbol}
  new_keys = {}
  sym_keys.each {|k| new_keys[k] = k.to_s}
  result = dup
  result.extend HashExtendedTools
  result.switch_keys new_keys
  result
end