diff options
Diffstat (limited to 'activesupport/lib/active_support/core_ext/module/delegation.rb')
-rw-r--r-- | activesupport/lib/active_support/core_ext/module/delegation.rb | 93 |
1 files changed, 77 insertions, 16 deletions
diff --git a/activesupport/lib/active_support/core_ext/module/delegation.rb b/activesupport/lib/active_support/core_ext/module/delegation.rb index 0d46248582..f5f4ba61b7 100644 --- a/activesupport/lib/active_support/core_ext/module/delegation.rb +++ b/activesupport/lib/active_support/core_ext/module/delegation.rb @@ -1,4 +1,5 @@ -require 'set' +require "set" +require "active_support/core_ext/regexp" class Module # Error generated by +delegate+ when a method is called on +nil+ and +allow_nil+ @@ -148,28 +149,24 @@ class Module # Foo.new("Bar").name # raises NoMethodError: undefined method `name' # # The target method must be public, otherwise it will raise +NoMethodError+. - # - def delegate(*methods) - options = methods.pop - unless options.is_a?(Hash) && to = options[:to] - raise ArgumentError, 'Delegation needs a target. Supply an options hash with a :to key as the last argument (e.g. delegate :hello, to: :greeter).' + def delegate(*methods, to: nil, prefix: nil, allow_nil: nil) + unless to + raise ArgumentError, "Delegation needs a target. Supply an options hash with a :to key as the last argument (e.g. delegate :hello, to: :greeter)." end - prefix, allow_nil = options.values_at(:prefix, :allow_nil) - - if prefix == true && to =~ /^[^a-z_]/ - raise ArgumentError, 'Can only automatically set the delegation prefix when delegating to a method.' + 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 - file, line = caller(1, 1).first.split(':'.freeze, 2) - line = line.to_i + location = caller_locations(1, 1).first + file, line = location.path, location.lineno to = to.to_s to = "self.#{to}" if DELEGATION_RESERVED_METHOD_NAMES.include?(to) @@ -177,7 +174,7 @@ class Module methods.each do |method| # Attribute writer methods only accept one argument. Makes sure []= # methods still accept two arguments. - definition = (method =~ /[^\]]=$/) ? 'arg' : '*args, &block' + definition = /[^\]]=$/.match?(method) ? "arg" : "*args, &block" # The following generated method calls the target exactly once, storing # the returned value in a dummy variable. @@ -194,7 +191,7 @@ class Module " _.#{method}(#{definition})", "end", "end" - ].join ';' + ].join ";" else exception = %(raise DelegationError, "#{self}##{method_prefix}#{method} delegated to #{to}.#{method}, but #{to} is nil: \#{self.inspect}") @@ -209,10 +206,74 @@ class Module " raise", " end", "end" - ].join ';' + ].join ";" end module_eval(method_def, file, line) end end + + # When building decorators, a common pattern may emerge: + # + # class Partition + # def initialize(first_event) + # @events = [ first_event ] + # end + # + # def people + # if @events.first.detail.people.any? + # @events.collect { |e| Array(e.detail.people) }.flatten.uniq + # else + # @events.collect(&:creator).uniq + # end + # end + # + # private + # def respond_to_missing?(name, include_private = false) + # @events.respond_to?(name, include_private) + # end + # + # def method_missing(method, *args, &block) + # @events.send(method, *args, &block) + # end + # end + # + # With `Module#delegate_missing_to`, the above is condensed to: + # + # class Partition + # delegate_missing_to :@events + # + # def initialize(first_event) + # @events = [ first_event ] + # end + # + # def people + # if @events.first.detail.people.any? + # @events.collect { |e| Array(e.detail.people) }.flatten.uniq + # else + # @events.collect(&:creator).uniq + # end + # end + # end + # + # The target can be anything callable within the object. E.g. instance + # variables, methods, constants ant the likes. + def delegate_missing_to(target) + target = target.to_s + target = "self.#{target}" if DELEGATION_RESERVED_METHOD_NAMES.include?(target) + + module_eval <<-RUBY, __FILE__, __LINE__ + 1 + def respond_to_missing?(name, include_private = false) + #{target}.respond_to?(name, include_private) + end + + def method_missing(method, *args, &block) + if #{target}.respond_to?(method) + #{target}.public_send(method, *args, &block) + else + super + end + end + RUBY + end end |