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

Inherits:
Cop
  • Object
show all
Includes:
UnusedArgument, Util
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::EQUALS_ASGN_NODES, Util::OPERATOR_METHODS, Util::PROC_NEW_NODE, Util::SHORTHAND_ASGN_NODES

Instance Attribute Summary

Attributes inherited from Cop

#config, #corrections, #offenses, #processed_source

Instance Method Summary collapse

Methods included from Util

block_length, command?, comment_line?, const_name, first_part_of_call_chain, lambda?, lambda_or_proc?, line_range, numeric_range_size, on_node, operator?, parentheses?, proc?, range_with_surrounding_space, source_range, strip_quotes

Methods included from PathUtil

match_path?, relative_path

Methods included from UnusedArgument

#after_leaving_scope, #autocorrect, #join_force?

Methods inherited from Cop

#add_offense, all, #autocorrect?, #config_to_allow_offenses, #config_to_allow_offenses=, #cop_config, cop_name, #cop_name, cop_type, #debug?, #display_cop_names?, #exclude_file?, #include_file?, inherited, #initialize, #join_force?, lint?, non_rails, qualified_cop_name, rails?, #relevant_file?, #support_autocorrect?

Methods included from IgnoredNode

#ignore_node, #ignored_node?, #part_of_ignored_node?

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?
  super
end

#message(variable) ⇒ Object 



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# File 'lib/rubocop/cop/lint/unused_block_argument.rb', line 22

def message(variable)
  message = "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?)

  if lambda?(scope.node)
    message << message_for_lambda(variable, all_arguments)
  else
    message << 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 61

def message_for_lambda(variable, all_arguments)
  message = 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 49

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 73

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 41

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