Class: RuboCop::Cop::Style::SuperArguments

Inherits:
Base
  • Object
show all
Extended by:
AutoCorrector
Defined in:
lib/rubocop/cop/style/super_arguments.rb

Overview

Checks for redundant argument forwarding when calling super with arguments identical to the method definition.

Using zero arity ‘super` within a `define_method` block results in `RuntimeError`:

source,ruby

def m

define_method(:foo) { super() } # => OK

end

def m

define_method(:foo) { super }   # => RuntimeError

end

Furthermore, any arguments accompanied by a block may potentially be delegating to ‘define_method`, therefore, `super` used within these blocks will be allowed. This approach might result in false negatives, yet ensuring safe detection takes precedence.

NOTE: When forwarding the same arguments but replacing the block argument with a new inline block, it is not necessary to explicitly list the non-block arguments. As such, an offense will be registered in this case.

Examples:

# bad
def method(*args, **kwargs)
  super(*args, **kwargs)
end

# good - implicitly passing all arguments
def method(*args, **kwargs)
  super
end

# good - forwarding a subset of the arguments
def method(*args, **kwargs)
  super(*args)
end

# good - forwarding no arguments
def method(*args, **kwargs)
  super()
end

# bad - forwarding with overridden block
def method(*args, **kwargs, &block)
  super(*args, **kwargs) { do_something }
end

# good - implicitly passing all non-block arguments
def method(*args, **kwargs, &block)
  super { do_something }
end

# good - assigning to the block variable before calling super
def method(&block)
  # Assigning to the block variable would pass the old value to super,
  # under this circumstance the block must be referenced explicitly.
  block ||= proc { 'fallback behavior' }
  super(&block)
end

Constant Summary collapse

ASSIGN_TYPES = 
%i[or_asgn lvasgn].freeze
MSG = 
'Call `super` without arguments and parentheses when the signature is identical.'
MSG_INLINE_BLOCK = 
'Call `super` without arguments and parentheses when all positional ' \
'and keyword arguments are forwarded.'

Constants inherited from Base

Base::RESTRICT_ON_SEND

Instance Attribute Summary

Attributes inherited from Base

#config, #processed_source

Instance Method Summary collapse

Methods included from AutoCorrector

support_autocorrect?

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

#on_super(super_node) ⇒ Object 



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# File 'lib/rubocop/cop/style/super_arguments.rb', line 77

def on_super(super_node)
  return unless (def_node = find_def_node(super_node))

  def_node_args = def_node.arguments.argument_list
  super_args = preprocess_super_args(super_node.arguments)

  return unless arguments_identical?(def_node, super_node, def_node_args, super_args)

  # If the number of arguments to the def node and super node are different here,
  # it's because the block argument is not forwarded.
  message = def_node_args.size == super_args.size ? MSG : MSG_INLINE_BLOCK
  add_offense(super_node, message: message) do |corrector|
    corrector.replace(super_node, 'super')
  end
end