Module: SimpleLock::Delegation

Included in:
Config, Redis
Defined in:
lib/initializers/delegation.rb

Defined Under Namespace

Classes: DelegationError

Constant Summary collapse

RUBY_RESERVED_KEYWORDS = 
%w[__ENCODING__ __LINE__ __FILE__ alias and BEGIN begin break
case class def defined? do else elsif END end ensure false for if in module next nil
not or redo rescue retry return self super then true undef unless until when while yield].freeze
DELEGATION_RESERVED_KEYWORDS = 
%w[_ arg args block].freeze
DELEGATION_RESERVED_METHOD_NAMES = 
Set.new(
  RUBY_RESERVED_KEYWORDS + DELEGATION_RESERVED_KEYWORDS
).freeze

Instance Method Summary collapse

Instance Method Details

#delegate(*methods, to: nil, prefix: nil, allow_nil: nil, private: nil) ⇒ Object 



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# File 'lib/initializers/delegation.rb', line 17

def delegate(*methods, to: nil, prefix: nil, allow_nil: nil, private: nil)
  unless to
    raise ArgumentError,
          "Delegation needs a target. Supply a keyword argument 'to' (e.g. delegate :hello, to: :greeter)."
  end

  if prefix == true && /^[^a-z_]/.match?(to)
    raise ArgumentError, "Can only automatically set the delegation prefix when delegating to a method."
  end

  method_prefix = \
    if prefix
      "#{prefix == true ? to : prefix}_"
    else
      ""
    end

  location = caller_locations(1, 1).first
  file = location.path
  line = location.lineno

  receiver = to.to_s
  receiver = "self.#{receiver}" if DELEGATION_RESERVED_METHOD_NAMES.include?(receiver)

  method_def = []
  method_names = []

  method_def << "self.private" if private

  methods.each do |method|
    method_name = prefix ? "#{method_prefix}#{method}" : method
    method_names << method_name.to_sym

    definition = \
      if /[^\]]=\z/.match?(method)
        "arg"
      else
        method_object =
          begin
            if to.is_a?(Module)
              to.method(method)
            elsif receiver == "self.class"
              method(method)
            end
          rescue NameError
            # Do nothing. Fall back to `"..."`
          end

        if method_object
          parameters = method_object.parameters

          if (parameters.map(&:first) & i[opt rest keyreq key keyrest]).any?
            "..."
          else
            defn = parameters.filter_map { |type, arg| arg if type == :req }
            defn << "&block"
            defn.join(", ")
          end
        else
          "..."
        end
      end

    method = method.to_s
    if allow_nil

      method_def <<
        "def #{method_name}(#{definition})" \
        "  _ = #{receiver}" \
        "  if !_.nil? || nil.respond_to?(:#{method})" \
        "    _.#{method}(#{definition})" \
        "  end" \
        "end"
    else
      method_name = method_name.to_s

      method_def <<
        "def #{method_name}(#{definition})" \
        "  _ = #{receiver}" \
        "  _.#{method}(#{definition})" \
        "rescue NoMethodError => e" \
        "  if _.nil? && e.name == :#{method}" <<
        %(   raise DelegationError, "#{self}##{method_name} delegated to #{receiver}.#{method}, but #{receiver} is nil: \#{self.inspect}") <<
        "  else" \
        "    raise" \
        "  end" \
        "end"
    end
  end
  module_eval(method_def.join(";"), file, line)
  method_names
end

#delegate_missing_to(target, allow_nil: nil) ⇒ Object 



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# File 'lib/initializers/delegation.rb', line 110

def delegate_missing_to(target, allow_nil: nil)
  target = target.to_s
  target = "self.#{target}" if DELEGATION_RESERVED_METHOD_NAMES.include?(target) || target == "__target"

  if allow_nil
    module_eval "      def respond_to_missing?(name, include_private = false)\n        # It may look like an oversight, but we deliberately do not pass\n        # +include_private+, because they do not get delegated.\n\n        return false if name == :marshal_dump || name == :_dump\n        \#{target}.respond_to?(name) || super\n      end\n\n      def method_missing(method, *args, &block)\n        __target = \#{target}\n        if __target.nil? && !nil.respond_to?(method)\n          nil\n        elsif __target.respond_to?(method)\n          __target.public_send(method, *args, &block)\n        else\n          super\n        end\n      end\n      ruby2_keywords(:method_missing)\n    RUBY\n  else\n    module_eval <<~RUBY, __FILE__, __LINE__ + 1\n      def respond_to_missing?(name, include_private = false)\n        # It may look like an oversight, but we deliberately do not pass\n        # +include_private+, because they do not get delegated.\n\n        return false if name == :marshal_dump || name == :_dump\n        \#{target}.respond_to?(name) || super\n      end\n\n      def method_missing(method, *args, &block)\n        __target = \#{target}\n        if __target.nil? && !nil.respond_to?(method)\n          raise DelegationError, \"\\\#{method} delegated to \#{target}, but \#{target} is nil\"\n        elsif __target.respond_to?(method)\n          __target.public_send(method, *args, &block)\n        else\n          super\n        end\n      end\n      ruby2_keywords(:method_missing)\n    RUBY\n  end\nend\n", __FILE__, __LINE__ + 1