Class: RuboCop::Cop::Style::IfUnlessModifier

Inherits:
Base
  • Object
show all
Extended by:
AutoCorrector
Includes:
AllowedPattern, CommentsHelp, LineLengthHelp, RangeHelp, RuboCop::Cop::StatementModifier
Defined in:
lib/rubocop/cop/style/if_unless_modifier.rb

Overview

Checks for ‘if` and `unless` statements that would fit on one line if written as modifier `if`/`unless`. The cop also checks for modifier `if`/`unless` lines that exceed the maximum line length.

The maximum line length is configured in the ‘Layout/LineLength` cop. The tab size is configured in the `IndentationWidth` of the `Layout/IndentationStyle` cop.

One-line pattern matching is always allowed. To ensure that there are few cases where the match variable is not used, and to prevent oversights. The variable ‘x` becomes undefined and raises `NameError` when the following example is changed to the modifier form:

source,ruby

if [42] in [x]

x # `x` is undefined when using modifier form.

end

The code ‘def method_name = body if condition` is considered a bad case by `Style/AmbiguousEndlessMethodDefinition` cop. So, to respect the user’s intention to use an endless method definition in the ‘if` body, the following code is allowed:

source,ruby

if condition

def method_name = body

end

NOTE: It is allowed when ‘defined?` argument has an undefined value, because using the modifier form causes the following incompatibility:

source,ruby

unless defined?(undefined_foo)

undefined_foo = 'default_value'

end undefined_foo # => ‘default_value’

undefined_bar = ‘default_value’ unless defined?(undefined_bar) undefined_bar # => nil

Examples:

# bad
if condition
  do_stuff(bar)
end

unless qux.empty?
  Foo.do_something
end

do_something_with_a_long_name(arg) if long_condition_that_prevents_code_fit_on_single_line

# good
do_stuff(bar) if condition
Foo.do_something unless qux.empty?

if long_condition_that_prevents_code_fit_on_single_line
  do_something_with_a_long_name(arg)
end

if short_condition # a long comment that makes it too long if it were just a single line
  do_something
end

Constant Summary collapse

MSG_USE_MODIFIER = 
'Favor modifier `%<keyword>s` usage when having a ' \
'single-line body. Another good alternative is ' \
'the usage of control flow `&&`/`||`.'
MSG_USE_NORMAL = 
'Modifier form of `%<keyword>s` makes the line too long.'

Constants included from RangeHelp

RangeHelp::BYTE_ORDER_MARK, RangeHelp::NOT_GIVEN

Constants included from Alignment

Alignment::SPACE

Constants inherited from Base

Base::RESTRICT_ON_SEND

Instance Attribute Summary

Attributes inherited from Base

#config, #processed_source

Class Method Summary collapse

Instance Method Summary collapse

Methods included from AutoCorrector

support_autocorrect?

Methods included from CommentsHelp

#comments_contain_disables?, #comments_in_range, #contains_comments?, #source_range_with_comment

Methods inherited from Base

#active_support_extensions_enabled?, #add_global_offense, #add_offense, #always_autocorrect?, 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?, #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

#exclude_limit

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

Class Method Details

.autocorrect_incompatible_with ⇒ Object 



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# File 'lib/rubocop/cop/style/if_unless_modifier.rb', line 87

def self.autocorrect_incompatible_with
  [Style::SoleNestedConditional]
end

Instance Method Details

#on_if(node) ⇒ Object

rubocop:disable Metrics/AbcSize



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# File 'lib/rubocop/cop/style/if_unless_modifier.rb', line 92

def on_if(node)
  return if endless_method?(node.body)

  condition = node.condition
  return if defined_nodes(condition).any? { |n| defined_argument_is_undefined?(node, n) } ||
            pattern_matching_nodes(condition).any?

  return unless (msg = message(node))

  add_offense(node.loc.keyword, message: format(msg, keyword: node.keyword)) do |corrector|
    next if part_of_ignored_node?(node)

    autocorrect(corrector, node)
    ignore_node(node)
  end
end
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