Class: RuboCop::Cop::Style::MutableConstant

Inherits:

Base

• Object
• Base
• RuboCop::Cop::Style::MutableConstant

Extended by:

AutoCorrector

Includes:

ConfigurableEnforcedStyle, FrozenStringLiteral

Defined in:

lib/rubocop/cop/style/mutable_constant.rb

Overview

Checks whether some constant value isn’t a mutable literal (e.g. array or hash).

Strict mode can be used to freeze all constants, rather than just literals. Strict mode is considered an experimental feature. It has not been updated with an exhaustive list of all methods that will produce frozen objects so there is a decent chance of getting some false positives. Luckily, there is no harm in freezing an already frozen object.

From Ruby 3.0, this cop honours the magic comment 'shareable_constant_value'. When this magic comment is set to any acceptable value other than none, it will suppress the offenses raised by this cop. It enforces frozen state.

Note	Regexp and Range literals are frozen objects since Ruby 3.0.

Note	From Ruby 3.0, interpolated strings are not frozen when # frozen-string-literal: true is used, so this cop enforces explicit freezing for such strings.

Note	From Ruby 3.0, this cop allows explicit freezing of constants when the shareable_constant_value directive is used.

Examples:

EnforcedStyle: literals (default)

# bad
CONST = [1, 2, 3]

# good
CONST = [1, 2, 3].freeze

# good
CONST = <<~TESTING.freeze
  This is a heredoc
TESTING

# good
CONST = Something.new

EnforcedStyle: strict

# bad
CONST = Something.new

# bad
CONST = Struct.new do
  def foo
    puts 1
  end
end

# good
CONST = Something.new.freeze

# good
CONST = Struct.new do
  def foo
    puts 1
  end
end.freeze

# Magic comment - shareable_constant_value: literal

# bad
CONST = [1, 2, 3]

# good
# shareable_constant_value: literal
CONST = [1, 2, 3]

Cop Safety Information:

• This cop’s autocorrection is unsafe since any mutations on objects that are made frozen will change from being accepted to raising FrozenError, and will need to be manually refactored.

Constant Summary

MSG =

'Freeze mutable objects assigned to constants.'

Constants included from FrozenStringLiteral

FrozenStringLiteral::FROZEN_STRING_LITERAL, FrozenStringLiteral::FROZEN_STRING_LITERAL_ENABLED

Constants inherited from Base

Base::RESTRICT_ON_SEND

Instance Attribute Summary

Attributes inherited from Base

#config, #processed_source

Instance Method Summary

• #on_casgn(node) ⇒ Object

Methods included from AutoCorrector

support_autocorrect?

Methods included from ConfigurableEnforcedStyle

#alternative_style, #alternative_styles, #ambiguous_style_detected, #correct_style_detected, #detected_style, #detected_style=, #no_acceptable_style!, #no_acceptable_style?, #opposite_style_detected, #style, #style_configured?, #style_detected, #style_parameter_name, #supported_styles, #unexpected_style_detected

Methods included from FrozenStringLiteral

frozen_string_literal_comment_exists?

Methods inherited from Base

#active_support_extensions_enabled?, #add_global_offense, #add_offense, autocorrect_incompatible_with, badge, #begin_investigation, callbacks_needed, #callbacks_needed, #config_to_allow_offenses, #config_to_allow_offenses=, #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, #ready, #relevant_file?, 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_casgn(node) ⇒ Object

# File 'lib/rubocop/cop/style/mutable_constant.rb', line 127

def on_casgn(node)
  _scope, _const_name, value = *node
  if value.nil? # This is only the case for `CONST += ...` or similarg66
    parent = node.parent
    return unless parent.or_asgn_type? # We only care about `CONST ||= ...`

    value = parent.children.last
  end

  on_assignment(value)
end