diff options
Diffstat (limited to 'activesupport/lib/active_support/core_ext/module/attribute_accessors_per_thread.rb')
| -rw-r--r-- | activesupport/lib/active_support/core_ext/module/attribute_accessors_per_thread.rb | 144 |
1 files changed, 144 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/core_ext/module/attribute_accessors_per_thread.rb b/activesupport/lib/active_support/core_ext/module/attribute_accessors_per_thread.rb new file mode 100644 index 0000000000..cb996e9e6d --- /dev/null +++ b/activesupport/lib/active_support/core_ext/module/attribute_accessors_per_thread.rb @@ -0,0 +1,144 @@ +# frozen_string_literal: true + +# Extends the module object with class/module and instance accessors for +# class/module attributes, just like the native attr* accessors for instance +# attributes, but does so on a per-thread basis. +# +# So the values are scoped within the Thread.current space under the class name +# of the module. +class Module + # Defines a per-thread class attribute and creates class and instance reader methods. + # The underlying per-thread class variable is set to +nil+, if it is not previously defined. + # + # module Current + # thread_mattr_reader :user + # end + # + # Current.user # => nil + # Thread.current[:attr_Current_user] = "DHH" + # Current.user # => "DHH" + # + # The attribute name must be a valid method name in Ruby. + # + # module Foo + # thread_mattr_reader :"1_Badname" + # end + # # => NameError: invalid attribute name: 1_Badname + # + # If you want to opt out of the creation of the instance reader method, pass + # <tt>instance_reader: false</tt> or <tt>instance_accessor: false</tt>. + # + # class Current + # thread_mattr_reader :user, instance_reader: false + # end + # + # Current.new.user # => NoMethodError + def thread_mattr_reader(*syms, instance_reader: true, instance_accessor: true) # :nodoc: + syms.each do |sym| + raise NameError.new("invalid attribute name: #{sym}") unless /^[_A-Za-z]\w*$/.match?(sym) + + # The following generated method concatenates `name` because we want it + # to work with inheritance via polymorphism. + class_eval(<<-EOS, __FILE__, __LINE__ + 1) + def self.#{sym} + Thread.current["attr_" + name + "_#{sym}"] + end + EOS + + if instance_reader && instance_accessor + class_eval(<<-EOS, __FILE__, __LINE__ + 1) + def #{sym} + self.class.#{sym} + end + EOS + end + end + end + alias :thread_cattr_reader :thread_mattr_reader + + # Defines a per-thread class attribute and creates a class and instance writer methods to + # allow assignment to the attribute. + # + # module Current + # thread_mattr_writer :user + # end + # + # Current.user = "DHH" + # Thread.current[:attr_Current_user] # => "DHH" + # + # If you want to opt out of the creation of the instance writer method, pass + # <tt>instance_writer: false</tt> or <tt>instance_accessor: false</tt>. + # + # class Current + # thread_mattr_writer :user, instance_writer: false + # end + # + # Current.new.user = "DHH" # => NoMethodError + def thread_mattr_writer(*syms, instance_writer: true, instance_accessor: true) # :nodoc: + syms.each do |sym| + raise NameError.new("invalid attribute name: #{sym}") unless /^[_A-Za-z]\w*$/.match?(sym) + + # The following generated method concatenates `name` because we want it + # to work with inheritance via polymorphism. + class_eval(<<-EOS, __FILE__, __LINE__ + 1) + def self.#{sym}=(obj) + Thread.current["attr_" + name + "_#{sym}"] = obj + end + EOS + + if instance_writer && instance_accessor + class_eval(<<-EOS, __FILE__, __LINE__ + 1) + def #{sym}=(obj) + self.class.#{sym} = obj + end + EOS + end + end + end + alias :thread_cattr_writer :thread_mattr_writer + + # Defines both class and instance accessors for class attributes. + # + # class Account + # thread_mattr_accessor :user + # end + # + # Account.user = "DHH" + # Account.user # => "DHH" + # Account.new.user # => "DHH" + # + # If a subclass changes the value, the parent class' value is not changed. + # Similarly, if the parent class changes the value, the value of subclasses + # is not changed. + # + # class Customer < Account + # end + # + # Customer.user = "Rafael" + # Customer.user # => "Rafael" + # Account.user # => "DHH" + # + # To opt out of the instance writer method, pass <tt>instance_writer: false</tt>. + # To opt out of the instance reader method, pass <tt>instance_reader: false</tt>. + # + # class Current + # thread_mattr_accessor :user, instance_writer: false, instance_reader: false + # end + # + # Current.new.user = "DHH" # => NoMethodError + # Current.new.user # => NoMethodError + # + # Or pass <tt>instance_accessor: false</tt>, to opt out both instance methods. + # + # class Current + # thread_mattr_accessor :user, instance_accessor: false + # end + # + # Current.new.user = "DHH" # => NoMethodError + # Current.new.user # => NoMethodError + def thread_mattr_accessor(*syms, instance_reader: true, instance_writer: true, instance_accessor: true) + thread_mattr_reader(*syms, instance_reader: instance_reader, instance_accessor: instance_accessor) + thread_mattr_writer(*syms, instance_writer: instance_writer, instance_accessor: instance_accessor) + end + alias :thread_cattr_accessor :thread_mattr_accessor +end |