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Class: RuboCop::Cop::Lint::InheritException

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

Overview

Looks for error classes inheriting from Exception. It is configurable to suggest using either StandardError (default) or RuntimeError instead.

When AllCops/UseProjectIndex is enabled and the rubydex gem is installed, indirect inheritance is also detected: a class whose parent (defined anywhere in the project) ultimately inherits from Exception is reported, without autocorrection.

Examples:

EnforcedStyle: standard_error (default)

# bad

class C < Exception; end

C = Class.new(Exception)

# good

class C < StandardError; end

C = Class.new(StandardError)

EnforcedStyle: runtime_error

# bad

class C < Exception; end

C = Class.new(Exception)

# good

class C < RuntimeError; end

C = Class.new(RuntimeError)

Cop Safety Information:

  • This cop’s autocorrection is unsafe because rescue that omit exception class handle StandardError and its subclasses, but not Exception and its subclasses.

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

::RuboCop::Cop::ConfigurableEnforcedStyle - Included

SYMBOL_TO_STRING_CACHE

::RuboCop::Cop::ProjectIndexHelp - Included

BUILTIN_DOCUMENT_URI, FILE_URI_PREFIX, WINDOWS_DRIVE_PREFIX

Class Attribute Summary

::RuboCop::Cop::AutoCorrector - Extended

support_autocorrect?

::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 a 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

::RuboCop::Cop::ConfigurableEnforcedStyle - Included

#detected_style, #detected_style=, #no_acceptable_style?, #style_configured?

::RuboCop::Cop::Base - Inherited

#active_support_extensions_enabled?, #always_autocorrect?, #config, #config_to_allow_offenses, #config_to_allow_offenses=, #contextual_autocorrect?, #processed_source, #project_index, #string_literals_frozen_by_default?, #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::ProjectIndexHelp - Included

#external_dependency_checksum, #compute_project_index_signature,
#definitions_in_other_files

Returns the definitions among definitions that live in a file other than the one being inspected, ordered by path and line.
#indexed_singleton_member

A namespace without any singleton method has no singleton-class declaration of its own, so the lookup starts from the first ancestor that has one; its find_member covers the rest of the chain.
#indexed_singleton_of

The declaration of `declaration’s singleton class, or nil when no singleton method is defined on it anywhere in the project.
#inherited_index_member?

Whether an ancestor of scope other than scope itself defines member_name.
#lexical_nesting_of

The lexical nesting the node’s constants resolve through, outermost first.
#prior_definition_in_other_file, #project_index_signature,
#resolve_constant_in_index

Resolves a constant node the way Ruby does: the first segment through the lexical nesting and every following segment inside the previous one.
#same_file?

::RuboCop::Cop::ConfigurableEnforcedStyle - Included

#alternative_style, #alternative_styles, #ambiguous_style_detected,
#conflicting_styles_detected

Alias for ConfigurableEnforcedStyle#no_acceptable_style!.
#correct_style_detected, #no_acceptable_style!, #opposite_style_detected, #style, #style_detected, #style_parameter_name, #supported_styles, #unexpected_style_detected,
#unrecognized_style_detected

Alias for ConfigurableEnforcedStyle#no_acceptable_style!.

::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_gem_version

Returns a gems locked versions (i.e.
#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, #matches_absolute_include_pattern?, #range_for_original, #range_from_node_or_range,
#reset_investigation

Actually private methods.
#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, #eol_comment, #eol_comment_would_be_inside_literal?, #heredoc_range, #line_with_eol_comment_too_long?, #max_line_length, #multiline_ranges, #multiline_string?,
#range_by_lines

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

#class_new_call?(node)

[ GitHub ] 

  


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



def_node_matcher :class_new_call?, <<~PATTERN
  (send
    (const {cbase nil?} :Class) :new
    $(const {cbase nil?} _))
PATTERN


  








  

    #exception_ancestor(declaration)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/inherit_exception.rb', line 121



def exception_ancestor(declaration)
  declaration.ancestors.find do |ancestor|
    ancestor.is_a?(Rubydex::Class) && exception_superclass_reference?(ancestor)
  end
end


  








  

    #exception_class?(class_node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/inherit_exception.rb', line 101



def exception_class?(class_node)
  class_node.const_name == 'Exception'
end


  








  

    #exception_superclass_reference?(ancestor)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/inherit_exception.rb', line 127



def exception_superclass_reference?(ancestor)
  ancestor.definitions.any? do |definition|
    next false unless definition.is_a?(Rubydex::ClassDefinition)

    superclass = definition.superclass
    superclass.is_a?(Rubydex::UnresolvedConstantReference) &&
      superclass.name.delete_prefix('::') == 'Exception'
  end
end


  








  

    #inherit_exception_class_with_omitted_namespace?(class_node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/inherit_exception.rb', line 137



def inherit_exception_class_with_omitted_namespace?(class_node)
  return false if class_node.parent_class.namespace&.cbase_type?

  class_node.left_siblings.any? do |sibling|
    sibling.respond_to?(:identifier) && exception_class?(sibling.identifier)
  end
end


  








  

    #inherits_exception_via(parent_class)   (private)
  



  

    


When AllCops/UseProjectIndex is enabled, indirect inheritance is
detected by walking the parent’s indexed ancestry: Exception itself
is not indexed, so a chain ending in it shows up as an ancestor whose
superclass reference is unresolved and literally named Exception.
Returns the name of that ancestor, or nil.



  



  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/inherit_exception.rb', line 110



def inherits_exception_via(parent_class)
  return nil unless project_index && parent_class.const_type?

  declaration = resolve_constant_in_index(parent_class)
  return nil unless declaration.is_a?(Rubydex::Class)

  exception_ancestor(declaration)&.name
rescue StandardError
  nil
end


  








  

    #message(node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/inherit_exception.rb', line 97



def message(node)
  format(MSG, prefer: preferred_base_class, current: node.const_name)
end


  








  

    #on_class(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/inherit_exception.rb', line 66



def on_class(node)
  parent_class = node.parent_class
  return unless parent_class

  if exception_class?(parent_class)
    return if inherit_exception_class_with_omitted_namespace?(node)

    add_offense(parent_class, message: message(parent_class)) do |corrector|
      corrector.replace(parent_class, preferred_base_class)
    end
  elsif (via = inherits_exception_via(parent_class))
    # No autocorrection: the `Exception` inheritance lives at another
    # class' definition site, possibly in another file.
    message = format(INDIRECT_MSG, prefer: preferred_base_class, via: via)
    add_offense(parent_class, message: message)
  end
end


  








  

    #on_send(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/inherit_exception.rb', line 84



def on_send(node)
  constant = class_new_call?(node)
  return unless constant && exception_class?(constant)

  message = message(constant)

  add_offense(constant, message: message) do |corrector|
    corrector.replace(constant, preferred_base_class)
  end
end


  








  

    #preferred_base_class   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/inherit_exception.rb', line 145



def preferred_base_class
  PREFERRED_BASE_CLASS[style]
end