Method: Module#thread_mattr_accessor

Defined in:

lib/active_support/core_ext/module/attribute_accessors_per_thread.rb

#thread_mattr_accessor(*syms, instance_reader: true, instance_writer: true, instance_accessor: true, default: nil) ⇒ Object Also known as: thread_cattr_accessor

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"

Unlike mattr_accessor, values are not shared with subclasses or parent classes. If a subclass changes the value, the parent class’ value is not changed. If the parent class changes the value, the value of subclasses is not changed.

class Customer < Account
end

Account.user   # => "DHH"
Customer.user  # => nil
Customer.user  = "Rafael"
Customer.user  # => "Rafael"
Account.user   # => "DHH"

To omit the instance writer method, pass instance_writer: false. To omit the instance reader method, pass instance_reader: false.

class Current
  thread_mattr_accessor :user, instance_writer: false, instance_reader: false
end

Current.new.user = "DHH"  # => NoMethodError
Current.new.user          # => NoMethodError

Or pass instance_accessor: false, to omit both instance methods.

class Current
  thread_mattr_accessor :user, instance_accessor: false
end

Current.new.user = "DHH"  # => NoMethodError
Current.new.user          # => NoMethodError

A default value may be specified using the :default option. Because multiple threads can access the default value, non-frozen default values will be duped and frozen.

# File 'lib/active_support/core_ext/module/attribute_accessors_per_thread.rb', line 170

def thread_mattr_accessor(*syms, instance_reader: true, instance_writer: true, instance_accessor: true, default: nil)
  thread_mattr_reader(*syms, instance_reader: instance_reader, instance_accessor: instance_accessor, default: default)
  thread_mattr_writer(*syms, instance_writer: instance_writer, instance_accessor: instance_accessor)
end