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Class: RuboCop::Cop::Style::ArrayCoercion

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/array_coercion.rb

Overview

Enforces the use of Array() instead of explicit Array check or [*var].

The cop is disabled by default due to safety concerns.

Examples:

# bad
paths = [paths] unless paths.is_a?(Array)
paths.each { |path| do_something(path) }

# bad (always creates a new Array instance)
[*paths].each { |path| do_something(path) }

# good (and a bit more readable)
Array(paths).each { |path| do_something(path) }

Cop Safety Information:

  • This cop is unsafe because a false positive may occur if the argument of Array() is (or could be) nil or depending on how the argument is handled by Array() (which can be different than just wrapping the argument in an array).

    For example:

    [nil]             #=> [nil]
    Array(nil)        #=> []
    
    [{a: 'b'}]        #= [{a: 'b'}]
    Array({a: 'b'})   #=> [[:a, 'b']]
    
    [Time.now]        #=> [#<Time ...>]
    Array(Time.now)   #=> [14, 16, 14, 16, 9, 2021, 4, 259, true, "EDT"]

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

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::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

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

Instance Method Details

#array_splat?(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/array_coercion.rb', line 48

def_node_matcher :array_splat?, <<~PATTERN
  (array (splat $_))
PATTERN

#on_array(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/array_coercion.rb', line 63

def on_array(node)
  return unless node.square_brackets?

  array_splat?(node) do |arg_node|
    message = format(SPLAT_MSG, arg: arg_node.source)
    add_offense(node, message: message) do |corrector|
      corrector.replace(node, "Array(#{arg_node.source})")
    end
  end
end

#on_if(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/array_coercion.rb', line 74

def on_if(node)
  unless_array?(node) do |var_a, var_b, var_c|
    if var_a == var_b && var_c == var_b
      message = format(CHECK_MSG, arg: var_a)
      add_offense(node, message: message) do |corrector|
        corrector.replace(node, "#{var_a} = Array(#{var_a})")
      end
    end
  end
end

#unless_array?(node)

[ GitHub ]

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

def_node_matcher :unless_array?, <<~PATTERN
  (if
    (send
      (lvar $_) :is_a?
      (const nil? :Array)) nil?
    (lvasgn $_
      (array
        (lvar $_))))
PATTERN