Class: RuboCop::Cop::Lint::UselessDefaultValueArgument

Inherits:
Base
  • Object
show all
Extended by:
AutoCorrector
Includes:
AllowedReceivers
Defined in:
lib/rubocop/cop/lint/useless_default_value_argument.rb

Overview

Checks for usage of method ‘fetch` or `Array.new` with default value argument and block. In such cases, block will always be used as default value.

This cop emulates Ruby warning “block supersedes default value argument” which applies to ‘Array.new`, `Array#fetch`, `Hash#fetch`, `ENV.fetch` and `Thread#fetch`.

A ‘fetch` call without a receiver is considered a custom method and does not register an offense.

Examples:

# bad
x.fetch(key, default_value) { block_value }
Array.new(size, default_value) { block_value }

# good
x.fetch(key) { block_value }
Array.new(size) { block_value }

# also good - in case default value argument is desired instead
x.fetch(key, default_value)
Array.new(size, default_value)

# good - keyword arguments aren't registered as offenses
x.fetch(key, keyword: :arg) { block_value }

AllowedReceivers: [‘Rails.cache’]

# good
Rails.cache.fetch(name, options) { block }

Constant Summary collapse

MSG = 
'Block supersedes default value argument.'
RESTRICT_ON_SEND = 
%i[fetch new].freeze

Instance Attribute Summary

Attributes inherited from Base

#config, #processed_source

Instance Method Summary collapse

Methods included from AutoCorrector

support_autocorrect?

Methods included from AllowedReceivers

#allowed_receiver?, #allowed_receivers, #receiver_name

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

#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

Instance Method Details

#default_value_argument_and_block(node) ⇒ Object 



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# File 'lib/rubocop/cop/lint/useless_default_value_argument.rb', line 59

def_node_matcher :default_value_argument_and_block, <<~PATTERN
  (any_block
    {
      (call !nil? :fetch $_key $_default_value)
      (send (const _ :Array) :new $_size $_default_value)
    }
    _args
    _block_body)
PATTERN

#on_send(node) ⇒ Object Also known as: on_csend 



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# File 'lib/rubocop/cop/lint/useless_default_value_argument.rb', line 69

def on_send(node)
  unless (prev_arg_node, default_value_node = default_value_argument_and_block(node.parent))
    return
  end
  return if allowed_receiver?(node.receiver)
  return if hash_without_braces?(default_value_node)

  add_offense(default_value_node) do |corrector|
    corrector.remove(prev_arg_node.source_range.end.join(default_value_node.source_range))
  end
end