class RuboCop::Cop::Style::NumberedParametersLimit

Detects use of an excessive amount of numbered parameters in a single block. Having too many numbered parameters can make code too cryptic and hard to read.

The cop defaults to registering an offense if there is more than 1 numbered parameter but this maximum can be configured by setting ‘Max`.

@example Max: 1 (default)

# bad
use_multiple_numbered_parameters { _1.call(_2, _3, _4) }

# good
array.each { use_array_element_as_numbered_parameter(_1) }
hash.each { use_only_hash_value_as_numbered_parameter(_2) }

Constants

DEFAULT_MAX_VALUE
MSG
NUMBERED_PARAMETER_PATTERN

Public Instance Methods

on_numblock(node) click to toggle source
# File lib/rubocop/cop/style/numbered_parameters_limit.rb, line 32
def on_numblock(node)
  param_count = numbered_parameter_nodes(node).uniq.count
  return if param_count <= max_count

  parameter = max_count > 1 ? 'parameters' : 'parameter'
  message = format(MSG, max: max_count, parameter: parameter, count: param_count)
  add_offense(node, message: message) { self.max = param_count }
end

Private Instance Methods

max_count() click to toggle source
# File lib/rubocop/cop/style/numbered_parameters_limit.rb, line 49
def max_count
  max = cop_config.fetch('Max', DEFAULT_MAX_VALUE)

  # Ruby does not allow more than 9 numbered parameters
  [max, 9].min
end
numbered_parameter_nodes(node) click to toggle source
# File lib/rubocop/cop/style/numbered_parameters_limit.rb, line 43
def numbered_parameter_nodes(node)
  node.each_descendant(:lvar).select do |lvar_node|
    lvar_node.source.match?(NUMBERED_PARAMETER_PATTERN)
  end
end