Class: RuboCop::Cop::Lint::UselessSetterCall

Inherits:
Base
  • Object
show all
Extended by:
AutoCorrector
Defined in:
lib/rubocop/cop/lint/useless_setter_call.rb

Overview

This cop checks for setter call to local variable as the final expression of a function definition. Its auto-correction is marked as unsafe because return value will be changed.

NOTE: There are edge cases in which the local variable references a value that is also accessible outside the local scope. This is not detected by the cop, and it can yield a false positive.

Examples:


# bad

def something
  x = Something.new
  x.attr = 5
end

# good

def something
  x = Something.new
  x.attr = 5
  x
end

Defined Under Namespace

Classes: MethodVariableTracker

Constant Summary collapse

MSG =
'Useless setter call to local variable `%<variable>s`.'
ASSIGNMENT_TYPES =
%i[lvasgn ivasgn cvasgn gvasgn].freeze

Constants inherited from Base

Base::RESTRICT_ON_SEND

Instance Attribute Summary

Attributes inherited from Base

#config, #processed_source

Instance Method Summary collapse

Methods included from AutoCorrector

support_autocorrect?

Methods inherited from Base

#add_global_offense, #add_offense, autocorrect_incompatible_with, badge, #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, 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?, #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

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


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# File 'lib/rubocop/cop/lint/useless_setter_call.rb', line 38

def on_def(node)
  return unless node.body

  last_expr = last_expression(node.body)
  return unless setter_call_to_local_variable?(last_expr)

  tracker = MethodVariableTracker.new(node.body)
  receiver, = *last_expr
  variable_name, = *receiver
  return unless tracker.contain_local_object?(variable_name)

  loc_name = receiver.loc.name

  add_offense(loc_name, message: format(MSG, variable: loc_name.source)) do |corrector|
    corrector.insert_after(last_expr, "\n#{indent(last_expr)}#{loc_name.source}")
  end
end