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Class: RuboCop::Cop::Lint::UselessRescue

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, ::RuboCop::Cop::Base, ::RuboCop::ExcludeLimit, NodePattern::Macros, RuboCop::AST::Sexp
Instance Chain:
self, ::RuboCop::Cop::Base, ::RuboCop::Cop::AutocorrectLogic, ::RuboCop::Cop::IgnoredNode, ::RuboCop::Util, RuboCop::AST::Sexp
Inherits: RuboCop::Cop::Base
Defined in: lib/rubocop/cop/lint/useless_rescue.rb

Overview

Checks for useless `rescue`s, which only reraise rescued exceptions.

Examples:

# bad
def foo
  do_something
rescue
  raise
end

# bad
def foo
  do_something
rescue => e
  raise # or 'raise e', or 'raise $!', or 'raise $ERROR_INFO'
end

# good
def foo
  do_something
rescue
  do_cleanup
  raise
end

# bad (latest rescue)
def foo
  do_something
rescue ArgumentError
  # noop
rescue
  raise
end

# good (not the latest rescue)
def foo
  do_something
rescue ArgumentError
  raise
rescue
  # noop
end

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

Class Attribute Summary

::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.
.builtin?

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

Cops (other than builtin) are encouraged to implement this.
.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

::RuboCop::Cop::Base - Inherited

#active_support_extensions_enabled?, #always_autocorrect?, #config, #config_to_allow_offenses, #config_to_allow_offenses=, #contextual_autocorrect?, #processed_source, #target_satisfies_all_gem_version_requirements?

::RuboCop::Cop::AutocorrectLogic - Included

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

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, #use_corrector

::RuboCop::Cop::AutocorrectLogic - Included

#disable_offense, #disable_offense_at_end_of_line, #disable_offense_before_and_after, #disable_offense_with_eol_or_surround_comment, #max_line_length,
#range_by_lines

Expand the given range to include all of any lines it covers.
#range_of_first_line, #surrounding_heredoc, #surrounding_percent_array

::RuboCop::Cop::IgnoredNode - Included

#ignore_node, #ignored_node?, #part_of_ignored_node?, #ignored_nodes

Constructor Details

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

Instance Method Details

#exception_objects(resbody_node) (private)

[ GitHub ] 

  


# File 'lib/rubocop/cop/lint/useless_rescue.rb', line 83



def exception_objects(resbody_node)
  [resbody_node.exception_variable&.source, '$!', '$ERROR_INFO']
end


  








  

    #on_rescue(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/useless_rescue.rb', line 52



def on_rescue(node)
  resbody_node = node.resbody_branches.last
  add_offense(resbody_node) if only_reraising?(resbody_node)
end


  








  

    #only_reraising?(resbody_node)  ⇒ Boolean  (private)
  



  

    


Metrics/CyclomaticComplexity



  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/useless_rescue.rb', line 60



def only_reraising?(resbody_node)
  return false if use_exception_variable_in_ensure?(resbody_node)

  body = resbody_node.body

  return false if body.nil? || !body.send_type? || !body.method?(:raise) || body.receiver
  return true unless body.arguments?
  return false if body.arguments.size > 1

  exception_name = body.first_argument.source

  exception_objects(resbody_node).include?(exception_name)
end


  








  

    #use_exception_variable_in_ensure?(resbody_node)  ⇒ Boolean  (private)
  



  

    


Metrics/CyclomaticComplexity



  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/useless_rescue.rb', line 75



def use_exception_variable_in_ensure?(resbody_node)
  return false unless (exception_variable = resbody_node.exception_variable)
  return false unless (ensure_node = resbody_node.each_ancestor(:ensure).first)
  return false unless (ensure_body = ensure_node.body)

  ensure_body.each_descendant(:lvar).map(&:source).include?(exception_variable.source)
end