class RuboCop::Cop::Style::MutableConstant
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.
@safety
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.
@example 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
@example 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
@example
# Magic comment - shareable_constant_value: literal # bad CONST = [1, 2, 3] # good # shareable_constant_value: literal CONST = [1, 2, 3]
Constants
- MSG
Public Instance Methods
# 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
Private Instance Methods
# File lib/rubocop/cop/style/mutable_constant.rb, line 169 def autocorrect(corrector, node) expr = node.source_range splat_value = splat_value(node) if splat_value correct_splat_expansion(corrector, expr, splat_value) elsif node.array_type? && !node.bracketed? corrector.wrap(expr, '[', ']') elsif requires_parentheses?(node) corrector.wrap(expr, '(', ')') end corrector.insert_after(expr, '.freeze') end
# File lib/rubocop/cop/style/mutable_constant.rb, line 158 def check(value) range_enclosed_in_parentheses = range_enclosed_in_parentheses?(value) return unless mutable_literal?(value) || (target_ruby_version <= 2.7 && range_enclosed_in_parentheses) return if frozen_string_literal?(value) return if shareable_constant_value?(value) add_offense(value) { |corrector| autocorrect(corrector, value) } end
# File lib/rubocop/cop/style/mutable_constant.rb, line 208 def correct_splat_expansion(corrector, expr, splat_value) if range_enclosed_in_parentheses?(splat_value) corrector.replace(expr, "#{splat_value.source}.to_a") else corrector.replace(expr, "(#{splat_value.source}).to_a") end end
# File lib/rubocop/cop/style/mutable_constant.rb, line 200 def frozen_regexp_or_range_literals?(node) target_ruby_version >= 3.0 && (node.regexp_type? || node.range_type?) end
# File lib/rubocop/cop/style/mutable_constant.rb, line 190 def immutable_literal?(node) frozen_regexp_or_range_literals?(node) || node.immutable_literal? end
# File lib/rubocop/cop/style/mutable_constant.rb, line 184 def mutable_literal?(value) return false if frozen_regexp_or_range_literals?(value) value.mutable_literal? end
# File lib/rubocop/cop/style/mutable_constant.rb, line 141 def on_assignment(value) if style == :strict strict_check(value) else check(value) end end
# File lib/rubocop/cop/style/mutable_constant.rb, line 204 def requires_parentheses?(node) node.range_type? || (node.send_type? && node.loc.dot.nil?) end
# File lib/rubocop/cop/style/mutable_constant.rb, line 149 def strict_check(value) return if immutable_literal?(value) return if operation_produces_immutable_object?(value) return if frozen_string_literal?(value) return if shareable_constant_value?(value) add_offense(value) { |corrector| autocorrect(corrector, value) } end