Class: RuboCop::Cop::Style::ClassVars

Inherits:
Base
  • Object
show all
Defined in:
lib/rubocop/cop/style/class_vars.rb

Overview

Checks for uses of class variables. Offenses are signaled only on assignment to class variables to reduce the number of offenses that would be reported.

You have to be careful when setting a value for a class variable; if a class has been inherited, changing the value of a class variable also affects the inheriting classes. This means that it’s almost always better to use a class instance variable instead.

Examples:

# bad
class A
  @@test = 10
end

class A
  def self.test(name, value)
    class_variable_set("@@#{name}", value)
  end
end

class A; end
A.class_variable_set(:@@test, 10)

# good
class A
  @test = 10
end

class A
  def test
    @@test # you can access class variable without offense
  end
end

class A
  def self.test(name)
    class_variable_get("@@#{name}") # you can access without offense
  end
end

Constant Summary collapse

MSG = 
'Replace class var %<class_var>s with a class instance var.'
RESTRICT_ON_SEND = 
%i[class_variable_set].freeze

Instance Attribute Summary

Attributes inherited from Base

#config, #processed_source

Instance Method Summary collapse

Methods inherited from Base

#active_support_extensions_enabled?, #add_global_offense, #add_offense, #always_autocorrect?, autocorrect_incompatible_with, badge, #begin_investigation, #callbacks_needed, callbacks_needed, #config_to_allow_offenses, #config_to_allow_offenses=, #contextual_autocorrect?, #cop_config, cop_name, #cop_name, department, documentation_url, exclude_from_registry, #excluded_file?, #external_dependency_checksum, inherited, #initialize, #inspect, joining_forces, lint?, match?, #message, #offenses, #on_investigation_end, #on_new_investigation, #on_other_file, #parse, #parser_engine, #ready, #relevant_file?, requires_gem, #string_literals_frozen_by_default?, support_autocorrect?, support_multiple_source?, #target_rails_version, #target_ruby_version

Methods included from ExcludeLimit

#exclude_limit

Methods included from AutocorrectLogic

#autocorrect?, #autocorrect_enabled?, #autocorrect_requested?, #autocorrect_with_disable_uncorrectable?, #correctable?, #disable_uncorrectable?, #safe_autocorrect?

Methods included from IgnoredNode

#ignore_node, #ignored_node?, #part_of_ignored_node?

Methods included from Util

silence_warnings

Constructor Details

This class inherits a constructor from RuboCop::Cop::Base

Instance Method Details

#on_cvasgn(node) ⇒ Object 



52
53
54
 
# File 'lib/rubocop/cop/style/class_vars.rb', line 52

def on_cvasgn(node)
  add_offense(node.loc.name, message: format(MSG, class_var: node.children.first))
end

#on_send(node) ⇒ Object 



56
57
58
59
60
 
# File 'lib/rubocop/cop/style/class_vars.rb', line 56

def on_send(node)
  return unless (first_argument = node.first_argument)

  add_offense(first_argument, message: format(MSG, class_var: first_argument.source))
end