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Class: RuboCop::Cop::Style::MethodDefParentheses

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, ::RuboCop::Cop::AutoCorrector, ::RuboCop::Cop::Base, ::RuboCop::ExcludeLimit, NodePattern::Macros, RuboCop::AST::Sexp
Instance Chain:
self, ::RuboCop::Cop::RangeHelp, ::RuboCop::Cop::ConfigurableEnforcedStyle, ::RuboCop::Cop::Base, ::RuboCop::Cop::AutocorrectLogic, ::RuboCop::Cop::IgnoredNode, ::RuboCop::Util, RuboCop::AST::Sexp
Inherits: RuboCop::Cop::Base
Defined in: lib/rubocop/cop/style/method_def_parentheses.rb

Overview

Checks for parentheses around the arguments in method definitions. Both instance and class/singleton methods are checked.

Regardless of style, parentheses are necessary for:

  1. Endless methods

  2. Argument lists containing a forward-arg (…​)

  3. Argument lists containing an anonymous rest arguments forwarding (*)

  4. Argument lists containing an anonymous keyword rest arguments forwarding (**)

  5. Argument lists containing an anonymous block forwarding (&)

Removing the parens would be a syntax error here.

Examples:

EnforcedStyle: require_parentheses (default)

# The {require_parentheses} style requires method definitions
# to always use parentheses

# bad
def bar num1, num2
  num1 + num2
end

def foo descriptive_var_name,
        another_descriptive_var_name,
        last_descriptive_var_name
  do_something
end

# good
def bar(num1, num2)
  num1 + num2
end

def foo(descriptive_var_name,
        another_descriptive_var_name,
        last_descriptive_var_name)
  do_something
end

EnforcedStyle: require_no_parentheses

# The {require_no_parentheses} style requires method definitions
# to never use parentheses

# bad
def bar(num1, num2)
  num1 + num2
end

def foo(descriptive_var_name,
        another_descriptive_var_name,
        last_descriptive_var_name)
  do_something
end

# good
def bar num1, num2
  num1 + num2
end

def foo descriptive_var_name,
        another_descriptive_var_name,
        last_descriptive_var_name
  do_something
end

EnforcedStyle: require_no_parentheses_except_multiline

# The {require_no_parentheses_except_multiline} style prefers no
# parentheses when method definition arguments fit on single line,
# but prefers parentheses when arguments span multiple lines.

# bad
def bar(num1, num2)
  num1 + num2
end

def foo descriptive_var_name,
        another_descriptive_var_name,
        last_descriptive_var_name
  do_something
end

# good
def bar num1, num2
  num1 + num2
end

def foo(descriptive_var_name,
        another_descriptive_var_name,
        last_descriptive_var_name)
  do_something
end

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

::RuboCop::Cop::ConfigurableEnforcedStyle - Included

SYMBOL_TO_STRING_CACHE

::RuboCop::Cop::RangeHelp - Included

BYTE_ORDER_MARK, NOT_GIVEN

Class Attribute Summary

::RuboCop::Cop::AutoCorrector - Extended

support_autocorrect?

::RuboCop::Cop::Base - Inherited

.gem_requirements, .lint?,
.support_autocorrect?

Returns if class supports autocorrect.
.support_multiple_source?

Override if your cop should be called repeatedly for multiple investigations Between calls to on_new_investigation and on_investigation_end, the result of processed_source will remain constant.

Class Method Summary

::RuboCop::Cop::Base - Inherited

.autocorrect_incompatible_with

List of cops that should not try to autocorrect at the same time as this cop.
.badge

Naming.
.callbacks_needed, .cop_name, .department,
.documentation_url

Returns a url to view this cops documentation online.
.exclude_from_registry

Call for abstract Cop classes.
.inherited,
.joining_forces

Override and return the Force class(es) you need to join.
.match?

Returns true if the cop name or the cop namespace matches any of the given names.
.new,
.requires_gem

Register a version requirement for the given gem name.
.restrict_on_send

::RuboCop::ExcludeLimit - Extended

exclude_limit

Sets up a configuration option to have an exclude limit tracked.
transform

Instance Attribute Summary

::RuboCop::Cop::ConfigurableEnforcedStyle - Included

#detected_style, #detected_style=, #no_acceptable_style?, #style_configured?

::RuboCop::Cop::Base - Inherited

#active_support_extensions_enabled?, #always_autocorrect?, #config, #config_to_allow_offenses, #config_to_allow_offenses=, #contextual_autocorrect?, #processed_source, #string_literals_frozen_by_default?, #target_satisfies_all_gem_version_requirements?

::RuboCop::Cop::AutocorrectLogic - Included

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

Instance Method Summary

::RuboCop::Cop::RangeHelp - Included

#add_range, #column_offset_between,
#contents_range

A range containing only the contents of a literal with delimiters (e.g.
#directions,
#effective_column

Returns the column attribute of the range, except if the range is on the first line and there’s a byte order mark at the beginning of that line, in which case 1 is subtracted from the column value.
#final_pos, #move_pos, #move_pos_str, #range_between, #range_by_whole_lines, #range_with_comments, #range_with_comments_and_lines, #range_with_surrounding_comma, #range_with_surrounding_space, #source_range

::RuboCop::Cop::ConfigurableEnforcedStyle - Included

#alternative_style, #alternative_styles, #ambiguous_style_detected,
#conflicting_styles_detected

Alias for ConfigurableEnforcedStyle#no_acceptable_style!.
#correct_style_detected, #no_acceptable_style!, #opposite_style_detected, #style, #style_detected, #style_parameter_name, #supported_styles, #unexpected_style_detected,
#unrecognized_style_detected

Alias for ConfigurableEnforcedStyle#no_acceptable_style!.

::RuboCop::Cop::Base - Inherited

#add_global_offense

Adds an offense that has no particular location.
#add_offense

Adds an offense on the specified range (or node with an expression) Unless that offense is disabled for this range, a corrector will be yielded to provide the cop the opportunity to autocorrect the offense.
#begin_investigation

Called before any investigation.
#callbacks_needed,
#cop_config

Configuration Helpers.
#cop_name, #excluded_file?,
#external_dependency_checksum

This method should be overridden when a cop’s behavior depends on state that lives outside of these locations:
#inspect,
#message

Gets called if no message is specified when calling add_offense or add_global_offense Cops are discouraged to override this; instead pass your message directly.
#name

Alias for Base#cop_name.
#offenses,
#on_investigation_end

Called after all on_…​
#on_new_investigation

Called before all on_…​
#on_other_file

Called instead of all on_…​
#parse

There should be very limited reasons for a Cop to do it’s own parsing.
#parser_engine,
#ready

Called between investigations.
#relevant_file?,
#target_gem_version

Returns a gems locked versions (i.e.
#target_rails_version, #target_ruby_version, #annotate, #apply_correction, #attempt_correction,
#callback_argument

Reserved for Cop::Cop.
#complete_investigation

Called to complete an investigation.
#correct, #current_corrector,
#current_offense_locations

Reserved for Commissioner:
#current_offenses, #currently_disabled_lines, #custom_severity, #default_severity, #disable_uncorrectable, #enabled_line?, #file_name_matches_any?, #find_message, #find_severity, #range_for_original, #range_from_node_or_range,
#reset_investigation

Actually private methods.
#use_corrector

::RuboCop::Cop::AutocorrectLogic - Included

#disable_offense, #disable_offense_at_end_of_line, #disable_offense_before_and_after, #disable_offense_with_eol_or_surround_comment, #heredoc_range, #max_line_length, #multiline_ranges, #multiline_string?,
#range_by_lines

Expand the given range to include all of any lines it covers.
#range_of_first_line, #range_overlaps_offense?, #string_continuation?, #surrounding_heredoc?, #surrounding_percent_array?

::RuboCop::Cop::IgnoredNode - Included

#ignore_node, #ignored_node?, #part_of_ignored_node?, #ignored_nodes

Constructor Details

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

Instance Method Details

#anonymous_arguments?(node) ⇒ Boolean (private)

[ GitHub ] 

  


# File 'lib/rubocop/cop/style/method_def_parentheses.rb', line 169



def anonymous_arguments?(node)
  return true if node.arguments.any? do |arg|
    arg.forward_arg_type? || arg.restarg_type? || arg.kwrestarg_type?
  end
  return false unless (last_argument = node.last_argument)

  last_argument.blockarg_type? && last_argument.name.nil?
end


  








  

    #arguments_without_parentheses?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/method_def_parentheses.rb', line 147



def arguments_without_parentheses?(node)
  node.arguments? && !parentheses?(node.arguments)
end


  








  

    #correct_arguments(arg_node, corrector)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/method_def_parentheses.rb', line 126



def correct_arguments(arg_node, corrector)
  corrector.replace(arg_node.loc.begin, ' ')
  corrector.remove(arg_node.loc.end)
end


  








  

    #forced_parentheses?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/method_def_parentheses.rb', line 131



def forced_parentheses?(node)
  # Regardless of style, parentheses are necessary for:
  # 1. Endless methods
  # 2. Argument lists containing a `forward-arg` (`...`)
  # 3. Argument lists containing an anonymous rest arguments forwarding (`*`)
  # 4. Argument lists containing an anonymous keyword rest arguments forwarding (`**`)
  # 5. Argument lists containing an anonymous block forwarding (`&`)
  # Removing the parens would be a syntax error here.
  node.endless? || anonymous_arguments?(node)
end


  








  

    #missing_parentheses(node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/method_def_parentheses.rb', line 151



def missing_parentheses(node)
  location = node.arguments.source_range

  add_offense(location, message: MSG_MISSING) do |corrector|
    add_parentheses(node.arguments, corrector)

    unexpected_style_detected 'require_no_parentheses'
  end
end


  








  

    #on_def(node)  
    Also known as: #on_defs
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/method_def_parentheses.rb', line 105



def on_def(node)
  return if forced_parentheses?(node)

  args = node.arguments

  if require_parentheses?(args)
    if arguments_without_parentheses?(node)
      missing_parentheses(node)
    else
      correct_style_detected
    end
  elsif parentheses?(args)
    unwanted_parentheses(args)
  else
    correct_style_detected
  end
end


  








  

    #on_defs(node)  
  



  

    


Alias for #on_def.



  



  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/method_def_parentheses.rb', line 122



alias on_defs on_def


  








  

    #require_parentheses?(args)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/method_def_parentheses.rb', line 142



def require_parentheses?(args)
  style == :require_parentheses ||
    (style == :require_no_parentheses_except_multiline && args.multiline?)
end


  








  

    #unwanted_parentheses(args)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/method_def_parentheses.rb', line 161



def unwanted_parentheses(args)
  add_offense(args, message: MSG_PRESENT) do |corrector|
    # offense is registered on args node when parentheses are unwanted
    correct_arguments(args, corrector)
    unexpected_style_detected 'require_parentheses'
  end
end