Class: RuboCop::Cop::Lint::UnderscorePrefixedVariableName

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

Overview

This cop checks for underscore-prefixed variables that are actually used.

Since block keyword arguments cannot be arbitrarily named at call sites, the `AllowKeywordBlockArguments` will allow use of underscore- prefixed block keyword arguments.

Examples:

AllowKeywordBlockArguments: false (default)


# bad

[1, 2, 3].each do |_num|
  do_something(_num)
end

query(:sales) do |_id:, revenue:, cost:|
  {_id: _id, profit: revenue - cost}
end

# good

[1, 2, 3].each do |num|
  do_something(num)
end

[1, 2, 3].each do |_num|
  do_something # not using `_num`
end

AllowKeywordBlockArguments: true


# good

query(:sales) do |_id:, revenue:, cost:|
  {_id: _id, profit: revenue - cost}
end

Constant Summary collapse

MSG =
'Do not use prefix `_` for a variable that is used.'

Constants included from Util

Util::LITERAL_REGEX

Instance Attribute Summary

Attributes inherited from Cop

#config, #corrections, #offenses, #processed_source

Instance Method Summary collapse

Methods inherited from Cop

#add_offense, all, autocorrect_incompatible_with, badge, #config_to_allow_offenses, #config_to_allow_offenses=, #cop_config, #cop_name, cop_name, #correct, department, #disable_uncorrectable, #duplicate_location?, #excluded_file?, #find_location, #highlights, inherited, #initialize, lint?, match?, #message, #messages, #parse, qualified_cop_name, #reason_to_not_correct, #relevant_file?, #target_rails_version, #target_ruby_version

Methods included from NodePattern::Macros

#def_node_matcher, #def_node_search, #node_search, #node_search_all, #node_search_body, #node_search_first

Methods included from AST::Sexp

#s

Methods included from AutocorrectLogic

#autocorrect?, #autocorrect_enabled?, #autocorrect_requested?, #correctable?, #disable_offense, #disable_uncorrectable?, #support_autocorrect?

Methods included from IgnoredNode

#ignore_node, #ignored_node?, #part_of_ignored_node?

Methods included from Util

begins_its_line?, comment_line?, double_quotes_required?, escape_string, first_part_of_call_chain, interpret_string_escapes, line_range, needs_escaping?, on_node, parentheses?, same_line?, to_string_literal, to_supported_styles, tokens, trim_string_interporation_escape_character

Methods included from PathUtil

absolute?, chdir, hidden_dir?, hidden_file_in_not_hidden_dir?, match_path?, pwd, relative_path, reset_pwd, smart_path

Constructor Details

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

Instance Method Details

#after_leaving_scope(scope, _variable_table) ⇒ Object


50
51
52
53
54
# File 'lib/rubocop/cop/lint/underscore_prefixed_variable_name.rb', line 50

def after_leaving_scope(scope, _variable_table)
  scope.variables.each_value do |variable|
    check_variable(variable)
  end
end

#check_variable(variable) ⇒ Object


56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
# File 'lib/rubocop/cop/lint/underscore_prefixed_variable_name.rb', line 56

def check_variable(variable)
  return unless variable.should_be_unused?
  return if variable.references.none?(&:explicit?)
  return if allowed_keyword_block_argument?(variable)

  node = variable.declaration_node

  location = if node.match_with_lvasgn_type?
               node.children.first.source_range
             else
               node.loc.name
             end

  add_offense(nil, location: location)
end

#join_force?(force_class) ⇒ Boolean

Returns:

  • (Boolean)

46
47
48
# File 'lib/rubocop/cop/lint/underscore_prefixed_variable_name.rb', line 46

def join_force?(force_class)
  force_class == VariableForce
end