Class: RuboCop::Cop::Lint::UnusedBlockArgument

Inherits:
Cop
  • Object
show all
Includes:
UnusedArgument
Defined in:
lib/rubocop/cop/lint/unused_block_argument.rb

Overview

This cop checks for unused block arguments.

Examples:


do_something do |used, unused, _unused_but_allowed|
  puts used
end

Constant Summary

Constants included from Util

Util::ASGN_NODES, Util::BYTE_ORDER_MARK, Util::EQUALS_ASGN_NODES, Util::LITERAL_REGEX, Util::OPERATOR_METHODS, Util::SHORTHAND_ASGN_NODES

Instance Attribute Summary

Attributes inherited from Cop

#config, #corrections, #offenses, #processed_source

Instance Method Summary collapse

Methods included from UnusedArgument

#after_leaving_scope, #autocorrect, #join_force?

Methods inherited from Cop

#add_offense, all, #config_to_allow_offenses, #config_to_allow_offenses=, #cop_config, cop_name, #cop_name, cop_type, #correct, #debug?, #details, #display_cop_names?, #display_style_guide?, #excluded_file?, #extra_details?, #highlights, inherited, #initialize, #join_force?, lint?, match?, #messages, non_rails, #parse, qualified_cop_name, #reference_url, #relevant_file?, #style_guide_url, #target_ruby_version

Methods included from Sexp

#s

Methods included from NodePattern::Macros

#def_node_matcher, #def_node_search, #node_search_body

Methods included from AutocorrectLogic

#autocorrect?, #autocorrect_enabled?, #autocorrect_requested?, #support_autocorrect?

Methods included from IgnoredNode

#ignore_node, #ignored_node?, #part_of_ignored_node?

Methods included from Util

begins_its_line?, block_length, comment_line?, directions, double_quotes_acceptable?, double_quotes_required?, effective_column, ends_its_line?, escape_string, first_part_of_call_chain, interpret_string_escapes, line_range, move_pos, needs_escaping?, numeric_range_size, on_node, operator?, parentheses?, parenthesized_call?, range_with_surrounding_comma, range_with_surrounding_space, source_range, strip_quotes, to_string_literal, to_symbol_literal, within_node?

Methods included from PathUtil

absolute?, match_path?, relative_path

Constructor Details

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

Instance Method Details

#check_argument(variable) ⇒ Object 



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# File 'lib/rubocop/cop/lint/unused_block_argument.rb', line 17

def check_argument(variable)
  return unless variable.block_argument?
  return if variable.keyword_argument? &&
            cop_config && cop_config['AllowUnusedKeywordArguments']

  if cop_config['IgnoreEmptyBlocks']
    _send, _args, body = *variable.scope.node
    return if body.nil?
  end

  super
end

#message(variable) ⇒ Object 



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# File 'lib/rubocop/cop/lint/unused_block_argument.rb', line 30

def message(variable)
  message = String.new("Unused #{variable_type(variable)} - " \
                       "`#{variable.name}`.")

  return message if variable.explicit_block_local_variable?

  message << ' '

  scope = variable.scope
  all_arguments = scope.variables.each_value.select(&:block_argument?)

  message << if scope.node.lambda?
               message_for_lambda(variable, all_arguments)
             else
               message_for_normal_block(variable, all_arguments)
             end

  message
end

#message_for_lambda(variable, all_arguments) ⇒ Object 



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# File 'lib/rubocop/cop/lint/unused_block_argument.rb', line 70

def message_for_lambda(variable, all_arguments)
  message = String.new(message_for_underscore_prefix(variable))

  if all_arguments.none?(&:referenced?)
    message << ' Also consider using a proc without arguments ' \
               'instead of a lambda if you want it ' \
                "to accept any arguments but don't care about them."
  end

  message
end

#message_for_normal_block(variable, all_arguments) ⇒ Object 



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# File 'lib/rubocop/cop/lint/unused_block_argument.rb', line 58

def message_for_normal_block(variable, all_arguments)
  if all_arguments.none?(&:referenced?)
    if all_arguments.count > 1
      "You can omit all the arguments if you don't care about them."
    else
      "You can omit the argument if you don't care about it."
    end
  else
    message_for_underscore_prefix(variable)
  end
end

#message_for_underscore_prefix(variable) ⇒ Object 



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# File 'lib/rubocop/cop/lint/unused_block_argument.rb', line 82

def message_for_underscore_prefix(variable)
  "If it's necessary, use `_` or `_#{variable.name}` " \
  "as an argument name to indicate that it won't be used."
end

#variable_type(variable) ⇒ Object 



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# File 'lib/rubocop/cop/lint/unused_block_argument.rb', line 50

def variable_type(variable)
  if variable.explicit_block_local_variable?
    'block local variable'
  else
    'block argument'
  end
end