Class: RuboCop::Cop::Style::GlobalVars

Inherits:
Base
  • Object
show all
Defined in:
lib/rubocop/cop/style/global_vars.rb

Overview

Looks for uses of global variables. Global variables introduce shared mutable state that makes code harder to test, debug, and reason about, since any part of the program can read or modify them.

It does not report offenses for built-in global variables. Built-in global variables are allowed by default. Additionally users can allow additional variables via the AllowedVariables option.

Note that backreferences like $1, $2, etc are not global variables.

Examples:

# bad
$foo = 2
bar = $foo + 5

# good
FOO = 2
foo = 2
$stdin.read

Constant Summary collapse

MSG = 
'Do not introduce global variables.'
BUILT_IN_VARS =

built-in global variables and their English aliases www.zenspider.com/ruby/quickref.html

%w[
  $: $LOAD_PATH
  $" $LOADED_FEATURES
  $0 $PROGRAM_NAME
  $! $ERROR_INFO
  $@ $ERROR_POSITION
  $; $FS $FIELD_SEPARATOR
  $, $OFS $OUTPUT_FIELD_SEPARATOR
  $/ $RS $INPUT_RECORD_SEPARATOR
  $\\ $ORS $OUTPUT_RECORD_SEPARATOR
  $. $NR $INPUT_LINE_NUMBER
  $_ $LAST_READ_LINE
  $> $DEFAULT_OUTPUT
  $< $DEFAULT_INPUT
  $$ $PID $PROCESS_ID
  $? $CHILD_STATUS
  $~ $LAST_MATCH_INFO
  $= $IGNORECASE
  $* $ARGV
  $& $MATCH
  $` $PREMATCH
  $' $POSTMATCH
  $+ $LAST_PAREN_MATCH
  $stdin $stdout $stderr
  $DEBUG $FILENAME $VERBOSE $SAFE
  $-0 $-a $-d $-F $-i $-I $-l $-p $-v $-w
  $CLASSPATH $JRUBY_VERSION $JRUBY_REVISION $ENV_JAVA
].map(&:to_sym)

Constants inherited from Base

Base::RESTRICT_ON_SEND

Instance Attribute Summary

Attributes inherited from Base

#config, #processed_source

Instance Method Summary collapse

Methods inherited from Base

#active_support_extensions_enabled?, #add_global_offense, #add_offense, #always_autocorrect?, autocorrect_incompatible_with, badge, #begin_investigation, #callbacks_needed, callbacks_needed, #config_to_allow_offenses, #config_to_allow_offenses=, #contextual_autocorrect?, #cop_config, cop_name, #cop_name, department, documentation_url, exclude_from_registry, #excluded_file?, #external_dependency_checksum, inherited, #initialize, #inspect, joining_forces, lint?, match?, #message, #offenses, #on_investigation_end, #on_new_investigation, #on_other_file, #parse, #parser_engine, #ready, #relevant_file?, requires_gem, #string_literals_frozen_by_default?, support_autocorrect?, support_multiple_source?, #target_gem_version, #target_rails_version, #target_ruby_version

Methods included from ExcludeLimit

cop_dir_for, #exclude_limit, read_limits

Methods included from AutocorrectLogic

#autocorrect?, #autocorrect_enabled?, #autocorrect_requested?, #autocorrect_with_disable_uncorrectable?, #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

#allowed_var?(global_var) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/rubocop/cop/style/global_vars.rb', line 63

def allowed_var?(global_var)
  BUILT_IN_VARS.include?(global_var) || user_vars.include?(global_var)
end

#check(node) ⇒ Object 



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# File 'lib/rubocop/cop/style/global_vars.rb', line 75

def check(node)
  add_offense(node.loc.name) unless allowed_var?(node.name)
end

#on_gvar(node) ⇒ Object 



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# File 'lib/rubocop/cop/style/global_vars.rb', line 67

def on_gvar(node)
  check(node)
end

#on_gvasgn(node) ⇒ Object 



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# File 'lib/rubocop/cop/style/global_vars.rb', line 71

def on_gvasgn(node)
  check(node)
end

#user_vars ⇒ Object 



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# File 'lib/rubocop/cop/style/global_vars.rb', line 59

def user_vars
  @user_vars ||= cop_config['AllowedVariables'].map(&:to_sym).freeze
end