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

Relationships & Source Files
Namespace Children
Classes:
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/lint/useless_setter_call.rb

Overview

Checks for setter call to local variable as the final expression of a function definition.

Examples:

# bad

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

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

Cop Safety Information:

  • 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.

    As well, autocorrection is unsafe because the method’s return value will be changed.

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

#last_expression(body) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/useless_setter_call.rb', line 67

def last_expression(body)
  expression = body.begin_type? ? body.children : body

  expression.is_a?(Array) ? expression.last : expression
end

#on_def(node) Also known as: #on_defs

[ GitHub ]

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

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

#on_defs(node)

Alias for #on_def.

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/useless_setter_call.rb', line 58

alias on_defs on_def

#setter_call_to_local_variable?(node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/useless_setter_call.rb', line 63

def_node_matcher :setter_call_to_local_variable?, <<~PATTERN
  [(send (lvar _) ...) setter_method?]
PATTERN