Class: RuboCop::Cop::Style::DoubleNegation

Inherits:
Base
  • Object
show all
Extended by:
AutoCorrector
Includes:
ConfigurableEnforcedStyle
Defined in:
lib/rubocop/cop/style/double_negation.rb

Overview

This cop checks for uses of double negation (`!!`) to convert something to a boolean value.

When using `EnforcedStyle: allowed_in_returns`, allow double nagation in contexts that use boolean as a return value. When using `EnforcedStyle: forbidden`, double nagation should be forbidden always.

Please, note that when something is a boolean value !!something and !something.nil? are not the same thing. As you're unlikely to write code that can accept values of any type this is rarely a problem in practice.

Examples:

# bad
!!something

# good
!something.nil?

EnforcedStyle: allowed_in_returns (default)

# good
def foo?
  !!return_value
end

EnforcedStyle: forbidden

# bad
def foo?
  !!return_value
end

Constant Summary collapse

MSG =
'Avoid the use of double negation (`!!`).'
RESTRICT_ON_SEND =
%i[!].freeze

Instance Attribute Summary

Attributes inherited from Base

#config, #processed_source

Instance Method Summary collapse

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 inherited from Base

#add_global_offense, #add_offense, autocorrect_incompatible_with, badge, #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, joining_forces, lint?, match?, #message, #offenses, #on_investigation_end, #on_new_investigation, #on_other_file, #ready, #relevant_file?, support_autocorrect?, support_multiple_source?, #target_rails_version, #target_ruby_version

Methods included from AutocorrectLogic

#autocorrect?, #autocorrect_enabled?, #autocorrect_requested?, #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_send(node) ⇒ Object


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# File 'lib/rubocop/cop/style/double_negation.rb', line 44

def on_send(node)
  return unless double_negative?(node) && node.prefix_bang?
  return if style == :allowed_in_returns && allowed_in_returns?(node)

  location = node.loc.selector
  add_offense(location) do |corrector|
    corrector.remove(location)
    corrector.insert_after(node, '.nil?')
  end
end