class RuboCop::Cop::Lint::UnderscorePrefixedVariableName

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.

@example 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

@example AllowKeywordBlockArguments: true

# good

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

Constants

MSG

Public Instance Methods

after_leaving_scope(scope, _variable_table) click to toggle source
# 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) click to toggle source
# 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) click to toggle source
# File lib/rubocop/cop/lint/underscore_prefixed_variable_name.rb, line 46
def join_force?(force_class)
  force_class == VariableForce
end

Private Instance Methods

allowed_keyword_block_argument?(variable) click to toggle source
# File lib/rubocop/cop/lint/underscore_prefixed_variable_name.rb, line 74
def allowed_keyword_block_argument?(variable)
  variable.block_argument? &&
    variable.keyword_argument? &&
    cop_config['AllowKeywordBlockArguments']
end