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Class: RuboCop::Cop::Style::ExplicitBlockArgument

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, ::RuboCop::Cop::AutoCorrector, ::RuboCop::Cop::Base, ::RuboCop::ExcludeLimit, NodePattern::Macros, RuboCop::AST::Sexp
Instance Chain:
Inherits: RuboCop::Cop::Base
Defined in: lib/rubocop/cop/style/explicit_block_argument.rb

Overview

Enforces the use of explicit block argument to avoid writing block literal that just passes its arguments to another block.

Note
This cop only registers an offense if the block args match the yield args exactly.

Examples:

# bad
def with_tmp_dir
  Dir.mktmpdir do |tmp_dir|
    Dir.chdir(tmp_dir) { |dir| yield dir } # block just passes arguments
  end
end

# bad
def nine_times
  9.times { yield }
end

# good
def with_tmp_dir(&block)
  Dir.mktmpdir do |tmp_dir|
    Dir.chdir(tmp_dir, &block)
  end
end

with_tmp_dir do |dir|
  puts "dir is accessible as a parameter and pwd is set: #{dir}"
end

# good
def nine_times(&block)
  9.times(&block)
end

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

::RuboCop::Cop::RangeHelp - Included

BYTE_ORDER_MARK, NOT_GIVEN

Class Attribute Summary

::RuboCop::Cop::AutoCorrector - Extended

::RuboCop::Cop::Base - Inherited

.gem_requirements, .lint?,
.support_autocorrect?

Returns if class supports autocorrect.

.support_multiple_source?

Override if your cop should be called repeatedly for multiple investigations Between calls to on_new_investigation and on_investigation_end, the result of processed_source will remain constant.

Class Method Summary

::RuboCop::Cop::Base - Inherited

.autocorrect_incompatible_with

List of cops that should not try to autocorrect at the same time as this cop.

.badge

Naming.

.callbacks_needed, .cop_name, .department,
.documentation_url

Returns an url to view this cops documentation online.

.exclude_from_registry

Call for abstract Cop classes.

.inherited,
.joining_forces

Override and return the Force class(es) you need to join.

.match?

Returns true if the cop name or the cop namespace matches any of the given names.

.new,
.requires_gem

Register a version requirement for the given gem name.

.restrict_on_send

::RuboCop::ExcludeLimit - Extended

exclude_limit

Sets up a configuration option to have an exclude limit tracked.

transform

Instance Attribute Summary

Instance Method Summary

::RuboCop::Cop::RangeHelp - Included

#add_range, #column_offset_between,
#contents_range

A range containing only the contents of a literal with delimiters (e.g.

#directions,
#effective_column

Returns the column attribute of the range, except if the range is on the first line and there’s a byte order mark at the beginning of that line, in which case 1 is subtracted from the column value.

#final_pos, #move_pos, #move_pos_str, #range_between, #range_by_whole_lines, #range_with_comments, #range_with_comments_and_lines, #range_with_surrounding_comma, #range_with_surrounding_space, #source_range

::RuboCop::Cop::Base - Inherited

#add_global_offense

Adds an offense that has no particular location.

#add_offense

Adds an offense on the specified range (or node with an expression) Unless that offense is disabled for this range, a corrector will be yielded to provide the cop the opportunity to autocorrect the offense.

#begin_investigation

Called before any investigation.

#callbacks_needed,
#cop_config

Configuration Helpers.

#cop_name, #excluded_file?,
#external_dependency_checksum

This method should be overridden when a cop’s behavior depends on state that lives outside of these locations:

#inspect
#message

Gets called if no message is specified when calling add_offense or add_global_offense Cops are discouraged to override this; instead pass your message directly.

#name

Alias for Base#cop_name.

#offenses,
#on_investigation_end

Called after all on_…​

#on_new_investigation

Called before all on_…​

#on_other_file

Called instead of all on_…​

#parse

There should be very limited reasons for a Cop to do it’s own parsing.

#parser_engine,
#ready

Called between investigations.

#relevant_file?, #target_rails_version, #target_ruby_version, #annotate, #apply_correction, #attempt_correction,
#callback_argument

Reserved for Cop::Cop.

#complete_investigation

Called to complete an investigation.

#correct, #current_corrector,
#current_offense_locations

Reserved for Commissioner:

#current_offenses, #currently_disabled_lines, #custom_severity, #default_severity, #disable_uncorrectable, #enabled_line?, #file_name_matches_any?, #find_message, #find_severity, #range_for_original, #range_from_node_or_range,
#reset_investigation

Actually private methods.

#use_corrector

::RuboCop::Cop::AutocorrectLogic - Included

::RuboCop::Cop::IgnoredNode - Included

Constructor Details

.new(config = nil, options = nil) ⇒ ExplicitBlockArgument

[ GitHub ]

  
# File 'lib/rubocop/cop/style/explicit_block_argument.rb', line 57

def initialize(config = nil, options = nil)
  super
  @def_nodes = Set.new
end

Class Method Details

.autocorrect_incompatible_with

[ GitHub ]

  
# File 'lib/rubocop/cop/style/explicit_block_argument.rb', line 53

def self.autocorrect_incompatible_with
  [Lint::UnusedMethodArgument]
end

Instance Method Details

#add_block_argument(node, corrector, block_name) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/explicit_block_argument.rb', line 108

def add_block_argument(node, corrector, block_name)
  if node.arguments?
    insert_argument(node, corrector, block_name)
  elsif empty_arguments?(node)
    corrector.replace(node.arguments, "(&#{block_name})")
  elsif call_like?(node)
    correct_call_node(node, corrector, block_name)
  else
    corrector.insert_after(node.loc.name, "(&#{block_name})")
  end
end

#block_body_range(block_node, send_node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/explicit_block_argument.rb', line 147

def block_body_range(block_node, send_node)
  range_between(send_node.source_range.end_pos, block_node.loc.end.end_pos)
end

#call_like?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/explicit_block_argument.rb', line 125

def call_like?(node)
  node.call_type? || node.zsuper_type? || node.super_type?
end

#correct_call_node(node, corrector, block_name) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/explicit_block_argument.rb', line 137

def correct_call_node(node, corrector, block_name)
  corrector.insert_after(node, "(&#{block_name})")
  return unless node.parenthesized?

  args_begin = Util.args_begin(node)
  args_end = Util.args_end(node)
  range = range_between(args_begin.begin_pos, args_end.end_pos)
  corrector.remove(range)
end

#empty_arguments?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/explicit_block_argument.rb', line 120

def empty_arguments?(node)
  # Is there an arguments node with only parentheses?
  node.arguments.is_a?(RuboCop::AST::Node) && node.arguments.loc.begin
end

#extract_block_name(def_node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/explicit_block_argument.rb', line 87

def extract_block_name(def_node)
  if def_node.block_argument?
    def_node.last_argument.name
  else
    'block'
  end
end

#insert_argument(node, corrector, block_name) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/explicit_block_argument.rb', line 129

def insert_argument(node, corrector, block_name)
  last_arg = node.last_argument
  arg_range = range_with_surrounding_comma(last_arg.source_range, :right)
  replacement = " &#{block_name}"
  replacement = ",#{replacement}" unless arg_range.source.end_with?(',')
  corrector.insert_after(arg_range, replacement) unless last_arg.blockarg_type?
end

#on_yield(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/explicit_block_argument.rb', line 62

def on_yield(node)
  block_node = node.parent

  yielding_block?(block_node) do |send_node, block_args, yield_args|
    return unless yielding_arguments?(block_args, yield_args)

    def_node = block_node.each_ancestor(:def, :defs).first
    # if `yield` is being called outside of a method context, ignore
    # this is not a valid ruby pattern, but can happen in haml or erb,
    # so this can cause crashes in haml_lint
    return unless def_node

    block_name = extract_block_name(def_node)

    add_offense(block_node) do |corrector|
      corrector.remove(block_body_range(block_node, send_node))

      add_block_argument(send_node, corrector, block_name)
      add_block_argument(def_node, corrector, block_name) if @def_nodes.add?(def_node)
    end
  end
end

#yielding_arguments?(block_args, yield_args) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/explicit_block_argument.rb', line 95

def yielding_arguments?(block_args, yield_args)
  yield_args = yield_args.dup.fill(
    nil,
    yield_args.length, block_args.length - yield_args.length
  )

  yield_args.zip(block_args).all? do |yield_arg, block_arg|
    next false unless yield_arg && block_arg

    block_arg && yield_arg.children.first == block_arg.children.first
  end
end

#yielding_block?(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/explicit_block_argument.rb', line 49

def_node_matcher :yielding_block?, <<~PATTERN
  (block $_ (args $...) (yield $...))
PATTERN