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Class: RuboCop::Cop::Naming::PredicateName

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

Overview

Checks that predicate methods names end with a question mark and do not start with a forbidden prefix.

A method is determined to be a predicate method if its name starts with one of the prefixes defined in the NamePrefix configuration. You can change what prefixes are considered by changing this option. Any method name that starts with one of these prefixes is required by the cop to end with a ?. Other methods can be allowed by adding to the AllowedMethods configuration.

Note
The is_a? method is allowed by default.

If ForbiddenPrefixes is set, methods that start with the configured prefixes will not be allowed and will be removed by autocorrection.

In other words, if ForbiddenPrefixes is empty, a method named is_foo will register an offense only due to the lack of question mark (and will be autocorrected to is_foo?). If ForbiddenPrefixes contains is_, is_foo will register an offense both because the ? is missing and because of the is_ prefix, and will be corrected to foo?.

Note
ForbiddenPrefixes is only applied to prefixes in NamePrefix; a prefix in the former but not the latter will not be considered by this cop.

Examples:

# bad
def is_even(value)
end

def is_even?(value)
end

# good
def even?(value)
end

# bad
def has_value
end

def has_value?
end

# good
def value?
end

AllowedMethods: ['is_a?'] (default)

# good
def is_a?(value)
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.

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::AllowedMethods - Included

::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

#allowed_method_name?(method_name, prefix) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/naming/predicate_name.rb', line 98

def allowed_method_name?(method_name, prefix)
  !(method_name.start_with?(prefix) && # cheap check to avoid allocating Regexp
      method_name.match?(/^#{prefix}[^0-9]/)) ||
    method_name == expected_name(method_name, prefix) ||
    method_name.end_with?('=') ||
    allowed_method?(method_name)
end

#dynamic_method_define(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/naming/predicate_name.rb', line 63

def_node_matcher :dynamic_method_define, <<~PATTERN
  (send nil? #method_definition_macros
    (sym $_)
    ...)
PATTERN

#expected_name(method_name, prefix) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/naming/predicate_name.rb', line 106

def expected_name(method_name, prefix)
  new_name = if forbidden_prefixes.include?(prefix)
               method_name.sub(prefix, '')
             else
               method_name.dup
             end
  new_name << '?' unless method_name.end_with?('?')
  new_name
end

#forbidden_prefixes (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/naming/predicate_name.rb', line 120

def forbidden_prefixes
  cop_config['ForbiddenPrefixes']
end

#message(method_name, new_name) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/naming/predicate_name.rb', line 116

def message(method_name, new_name)
  "Rename `#{method_name}` to `#{new_name}`."
end

#method_definition_macros(macro_name) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/naming/predicate_name.rb', line 128

def method_definition_macros(macro_name)
  cop_config['MethodDefinitionMacros'].include?(macro_name.to_s)
end

#on_def(node) Also known as: #on_defs

[ GitHub ]

  
# File 'lib/rubocop/cop/naming/predicate_name.rb', line 82

def on_def(node)
  predicate_prefixes.each do |prefix|
    method_name = node.method_name.to_s

    next if allowed_method_name?(method_name, prefix)

    add_offense(
      node.loc.name,
      message: message(method_name, expected_name(method_name, prefix))
    )
  end
end

#on_defs(node)

Alias for #on_def.

[ GitHub ]

  
# File 'lib/rubocop/cop/naming/predicate_name.rb', line 94

alias on_defs on_def

#on_send(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/naming/predicate_name.rb', line 69

def on_send(node)
  dynamic_method_define(node) do |method_name|
    predicate_prefixes.each do |prefix|
      next if allowed_method_name?(method_name.to_s, prefix)

      add_offense(
        node.first_argument.source_range,
        message: message(method_name, expected_name(method_name.to_s, prefix))
      )
    end
  end
end

#predicate_prefixes (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/naming/predicate_name.rb', line 124

def predicate_prefixes
  cop_config['NamePrefix']
end