Module: ActiveSupport::Memoizable

Defined in:
lib/active_support/memoizable.rb

Defined Under Namespace

Modules: Freezable

Constant Summary collapse

MEMOIZED_IVAR = 
Proc.new do |symbol|
  "@_memoized_#{symbol.to_s.sub(/\?\Z/, '_query').sub(/!\Z/, '_bang')}".to_sym
end

Instance Method Summary collapse

Instance Method Details

#memoize(*symbols) ⇒ Object 



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# File 'lib/active_support/memoizable.rb', line 44

def memoize(*symbols)
  symbols.each do |symbol|
    original_method = :"_unmemoized_#{symbol}"
    memoized_ivar = MEMOIZED_IVAR.call(symbol)

    class_eval <<-EOS, __FILE__, __LINE__
      include Freezable

      raise "Already memoized #{symbol}" if method_defined?(:#{original_method})
      alias #{original_method} #{symbol}

      if instance_method(:#{symbol}).arity == 0
        def #{symbol}(reload = false)
          if reload || !defined?(#{memoized_ivar}) || #{memoized_ivar}.empty?
            #{memoized_ivar} = [#{original_method}.freeze]
          end
          #{memoized_ivar}[0]
        end
      else
        def #{symbol}(*args)
          #{memoized_ivar} ||= {} unless frozen?
          reload = args.pop if args.last == true || args.last == :reload

          if defined?(#{memoized_ivar}) && #{memoized_ivar}
            if !reload && #{memoized_ivar}.has_key?(args)
              #{memoized_ivar}[args]
            elsif #{memoized_ivar}
              #{memoized_ivar}[args] = #{original_method}(*args).freeze
            end
          else
            #{original_method}(*args)
          end
        end
      end
    EOS
  end
end