class RuboCop::Cop::Naming::BlockForwarding

In Ruby 3.1, anonymous block forwarding has been added.

This cop identifies places where `do_something(&block)` can be replaced by `do_something(&)`.

It also supports the opposite style by alternative `explicit` option. You can specify the block variable name for autocorrection with `BlockForwardingName`. The default variable name is `block`. If the name is already in use, it will not be autocorrected.

@example EnforcedStyle: anonymous (default)

# bad
def foo(&block)
  bar(&block)
end

# good
def foo(&)
  bar(&)
end

@example EnforcedStyle: explicit

# bad
def foo(&)
  bar(&)
end

# good
def foo(&block)
  bar(&block)
end

Constants

MSG

Public Instance Methods

on_def(node) click to toggle source
# File lib/rubocop/cop/naming/block_forwarding.rb, line 50
def on_def(node)
  return if node.arguments.empty?

  last_argument = node.arguments.last
  return if expected_block_forwarding_style?(node, last_argument)

  register_offense(last_argument, node)

  node.each_descendant(:block_pass) do |block_pass_node|
    next if block_pass_node.children.first&.sym_type? ||
            last_argument.source != block_pass_node.source

    register_offense(block_pass_node, node)
  end
end
Also aliased as: on_defs
on_defs(node)
Alias for: on_def

Private Instance Methods

anonymous_block_argument?(node) click to toggle source
# File lib/rubocop/cop/naming/block_forwarding.rb, line 83
def anonymous_block_argument?(node)
  node.blockarg_type? && node.name.nil?
end
block_forwarding_name() click to toggle source
# File lib/rubocop/cop/naming/block_forwarding.rb, line 115
def block_forwarding_name
  cop_config.fetch('BlockForwardingName', 'block')
end
expected_block_forwarding_style?(node, last_argument) click to toggle source
# File lib/rubocop/cop/naming/block_forwarding.rb, line 69
def expected_block_forwarding_style?(node, last_argument)
  if style == :anonymous
    !explicit_block_argument?(last_argument) ||
      use_kwarg_in_method_definition?(node) ||
      use_block_argument_as_local_variable?(node, last_argument.source[1..])
  else
    !anonymous_block_argument?(last_argument)
  end
end
explicit_block_argument?(node) click to toggle source
# File lib/rubocop/cop/naming/block_forwarding.rb, line 87
def explicit_block_argument?(node)
  node.blockarg_type? && !node.name.nil?
end
register_offense(block_argument, node) click to toggle source
# File lib/rubocop/cop/naming/block_forwarding.rb, line 91
def register_offense(block_argument, node)
  add_offense(block_argument, message: format(MSG, style: style)) do |corrector|
    if style == :anonymous
      corrector.replace(block_argument, '&')

      arguments = block_argument.parent

      add_parentheses(arguments, corrector) unless arguments.parenthesized_call?
    else
      unless use_block_argument_as_local_variable?(node, block_forwarding_name)
        corrector.replace(block_argument, "&#{block_forwarding_name}")
      end
    end
  end
end
use_block_argument_as_local_variable?(node, last_argument) click to toggle source
# File lib/rubocop/cop/naming/block_forwarding.rb, line 107
def use_block_argument_as_local_variable?(node, last_argument)
  return if node.body.nil?

  node.body.each_descendant(:lvar, :lvasgn).any? do |lvar|
    !lvar.parent.block_pass_type? && lvar.source == last_argument
  end
end
use_kwarg_in_method_definition?(node) click to toggle source
# File lib/rubocop/cop/naming/block_forwarding.rb, line 79
def use_kwarg_in_method_definition?(node)
  node.arguments.each_descendant(:kwarg, :kwoptarg).any?
end