method

thread_mattr_reader

v7.2.3 - Show latest stable - Class: Module

thread_mattr_reader(*syms, instance_reader: true, instance_accessor: true, default: nil)

public

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 = "DHH"
Current.user # => "DHH"
Thread.new { Current.user }.value # => nil

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

To omit the instance reader method, pass instance_reader: false or instance_accessor: false.

class Current
  thread_mattr_reader :user, instance_reader: false
end

Current.new.user # => NoMethodError

# File activesupport/lib/active_support/core_ext/module/attribute_accessors_per_thread.rb, line 41
  def thread_mattr_reader(*syms, instance_reader: true, instance_accessor: true, default: nil) # :nodoc:
    syms.each do |sym|
      raise NameError.new("invalid attribute name: #{sym}") unless /^[_A-Za-z]\w*$/.match?(sym)

      # The following generated method concatenates `object_id` because we want
      # subclasses to maintain independent values.
      if default.nil?
        class_eval(          def self.#{sym}            @__thread_mattr_#{sym} ||= "attr_#{sym}_\#{object_id}"            ::ActiveSupport::IsolatedExecutionState[@__thread_mattr_#{sym}]          end, __FILE__, __LINE__ + 1)
      else
        default = default.dup.freeze unless default.frozen?
        singleton_class.define_method("#{sym}_default_value") { default }

        class_eval(          def self.#{sym}            @__thread_mattr_#{sym} ||= "attr_#{sym}_\#{object_id}"            value = ::ActiveSupport::IsolatedExecutionState[@__thread_mattr_#{sym}]            if value.nil? && !::ActiveSupport::IsolatedExecutionState.key?(@__thread_mattr_#{sym})              ::ActiveSupport::IsolatedExecutionState[@__thread_mattr_#{sym}] = #{sym}_default_value            else              value            end          end, __FILE__, __LINE__ + 1)
      end

      if instance_reader && instance_accessor
        class_eval(          def #{sym}            self.class.#{sym}          end, __FILE__, __LINE__ + 1)
      end
    end
  end

thread_mattr_reader

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