Class: RuboCop::Cop::Lint::HashCompareByIdentity

Inherits:
Base
  • Object
show all
Defined in:
lib/rubocop/cop/lint/hash_compare_by_identity.rb

Overview

Prefer using Hash#compare_by_identity rather than using object_id for hash keys.

This cop looks for hashes being keyed by objects' object_id, using one of these methods: key?, has_key?, fetch, [] and []=.

Examples:

# bad
hash = {}
hash[foo.object_id] = :bar
hash.key?(baz.object_id)

# good
hash = {}.compare_by_identity
hash[foo] = :bar
hash.key?(baz)

Cop Safety Information:

  • This cop is unsafe. Although unlikely, the hash could store both object ids and other values that need be compared by value, and thus could be a false positive.

    Furthermore, this cop cannot guarantee that the receiver of one of the methods (key?, etc.) is actually a hash.

Constant Summary collapse

RESTRICT_ON_SEND = 
%i[key? has_key? fetch [] []=].freeze
MSG = 
'Use `Hash#compare_by_identity` instead of using `object_id` for keys.'

Instance Attribute Summary

Attributes inherited from Base

#config, #processed_source

Instance Method Summary collapse

Methods inherited from Base

#active_support_extensions_enabled?, #add_global_offense, #add_offense, autocorrect_incompatible_with, badge, #begin_investigation, callbacks_needed, #callbacks_needed, #config_to_allow_offenses, #config_to_allow_offenses=, #cop_config, cop_name, #cop_name, department, documentation_url, exclude_from_registry, #excluded_file?, #external_dependency_checksum, inherited, #initialize, #inspect, joining_forces, lint?, match?, #message, #offenses, #on_investigation_end, #on_new_investigation, #on_other_file, #parse, #ready, #relevant_file?, support_autocorrect?, support_multiple_source?, #target_rails_version, #target_ruby_version

Methods included from ExcludeLimit

#exclude_limit

Methods included from AutocorrectLogic

#autocorrect?, #autocorrect_enabled?, #autocorrect_requested?, #autocorrect_with_disable_uncorrectable?, #correctable?, #disable_uncorrectable?, #safe_autocorrect?

Methods included from IgnoredNode

#ignore_node, #ignored_node?, #part_of_ignored_node?

Methods included from Util

silence_warnings

Constructor Details

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

Instance Method Details

#id_as_hash_key?(node) ⇒ Object 



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# File 'lib/rubocop/cop/lint/hash_compare_by_identity.rb', line 37

def_node_matcher :id_as_hash_key?, <<~PATTERN
  (send _ {:key? :has_key? :fetch :[] :[]=} (send _ :object_id) ...)
PATTERN

#on_send(node) ⇒ Object 



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# File 'lib/rubocop/cop/lint/hash_compare_by_identity.rb', line 41

def on_send(node)
  add_offense(node) if id_as_hash_key?(node)
end