Class: RuboCop::Cop::Naming::MemoizedInstanceVariableName

Inherits:
Cop
  • Object
show all
Defined in:
lib/rubocop/cop/naming/memoized_instance_variable_name.rb

Overview

This cop checks for memoized methods whose instance variable name does not match the method name.

Examples:

# bad
# Method foo is memoized using an instance variable that is
# not `@foo`. This can cause confusion and bugs.
def foo
  @something ||= calculate_expensive_thing
end

# good
def foo
  @foo ||= calculate_expensive_thing
end

# good
def foo
  @foo ||= begin
    calculate_expensive_thing
  end
end

# good
def foo
  helper_variable = something_we_need_to_calculate_foo
  @foo ||= calculate_expensive_thing(helper_variable)
end

Constant Summary

MSG =
'Memoized variable `%<var>s` does not match ' \
'method name `%<method>s`. Use `@%<suggested_var>s` instead.'.freeze

Constants included from Util

Util::ASGN_NODES, Util::CONDITIONAL_NODES, Util::EQUALS_ASGN_NODES, Util::LITERAL_REGEX, Util::LOGICAL_OPERATOR_NODES, Util::MODIFIER_NODES, Util::OPERATOR_METHODS, Util::SHORTHAND_ASGN_NODES

Instance Attribute Summary

Attributes inherited from Cop

#config, #corrections, #offenses, #processed_source

Instance Method Summary collapse

Methods inherited from Cop

#add_offense, all, autocorrect_incompatible_with, badge, #config_to_allow_offenses, #config_to_allow_offenses=, #cop_config, cop_name, #cop_name, #correct, department, #duplicate_location?, #excluded_file?, #find_location, #highlights, inherited, #initialize, #join_force?, lint?, match?, #message, #messages, non_rails, #parse, qualified_cop_name, #relevant_file?, #target_rails_version, #target_ruby_version

Methods included from NodePattern::Macros

#def_node_matcher, #def_node_search, #node_search, #node_search_all, #node_search_body, #node_search_first

Methods included from AST::Sexp

#s

Methods included from AutocorrectLogic

#autocorrect?, #autocorrect_enabled?, #autocorrect_requested?, #support_autocorrect?

Methods included from IgnoredNode

#ignore_node, #ignored_node?, #part_of_ignored_node?

Methods included from Util

begins_its_line?, comment_line?, double_quotes_required?, escape_string, first_part_of_call_chain, interpret_string_escapes, line_range, needs_escaping?, on_node, operator?, parentheses?, same_line?, to_string_literal, to_supported_styles, tokens

Methods included from PathUtil

absolute?, match_path?, pwd, relative_path, reset_pwd, smart_path

Constructor Details

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

Instance Method Details

#on_def(node) ⇒ Object Also known as: on_defs



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# File 'lib/rubocop/cop/naming/memoized_instance_variable_name.rb', line 52

def on_def(node)
  (method_name, ivar_assign) = memoized?(node)
  return if matches?(method_name, ivar_assign)
  msg = format(
    MSG,
    var: ivar_assign.children.first.to_s,
    suggested_var: method_name.to_s.delete('!?'),
    method: method_name
  )
  add_offense(node, location: ivar_assign.source_range, message: msg)
end