class RuboCop::Cop::Style::SuperArguments
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.
@example
# 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 # 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
Constants
- ASSIGN_TYPES
- DEF_TYPES
- MSG
Public Instance Methods
on_super(super_node)
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# File lib/rubocop/cop/style/super_arguments.rb, line 62 def on_super(super_node) def_node = super_node.ancestors.find do |node| # When defining dynamic methods, implicitly calling `super` is not possible. # Since there is a possibility of delegation to `define_method`, # `super` used within the block is always allowed. break if node.block_type? break node if DEF_TYPES.include?(node.type) end return unless def_node return unless arguments_identical?(def_node, def_node.arguments.argument_list, super_node.arguments) add_offense(super_node) { |corrector| corrector.replace(super_node, 'super') } end
Private Instance Methods
arguments_identical?(def_node, def_args, super_args)
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rubocop:disable Metrics/CyclomaticComplexity, Metrics/PerceivedComplexity
# File lib/rubocop/cop/style/super_arguments.rb, line 81 def arguments_identical?(def_node, def_args, super_args) super_args = preprocess_super_args(super_args) return false if def_args.size != super_args.size def_args.zip(super_args).each do |def_arg, super_arg| next if positional_arg_same?(def_arg, super_arg) next if positional_rest_arg_same(def_arg, super_arg) next if keyword_arg_same?(def_arg, super_arg) next if keyword_rest_arg_same?(def_arg, super_arg) next if block_arg_same?(def_node, def_arg, super_arg) next if forward_arg_same?(def_arg, super_arg) return false end true end
block_arg_same?(def_node, def_arg, super_arg)
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# File lib/rubocop/cop/style/super_arguments.rb, line 136 def block_arg_same?(def_node, def_arg, super_arg) return false unless def_arg.blockarg_type? && super_arg.block_pass_type? # anonymous forwarding return true if (block_pass_child = super_arg.children.first).nil? && def_arg.name.nil? block_arg_name = block_pass_child.children.first def_arg.name == block_arg_name && !block_reassigned?(def_node, block_arg_name) end
block_reassigned?(def_node, block_arg_name)
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Reassigning the block argument will still pass along the original block to super bugs.ruby-lang.org/issues/20505
# File lib/rubocop/cop/style/super_arguments.rb, line 147 def block_reassigned?(def_node, block_arg_name) def_node.each_node(*ASSIGN_TYPES).any? do |assign_node| # TODO: Since `Symbol#name` is supported from Ruby 3.0, the inheritance check for # `AST::Node` can be removed when requiring Ruby 3.0+. lhs = assign_node.node_parts[0] next if lhs.is_a?(AST::Node) && !lhs.respond_to?(:name) assign_node.name == block_arg_name end end
forward_arg_same?(def_arg, super_arg)
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# File lib/rubocop/cop/style/super_arguments.rb, line 158 def forward_arg_same?(def_arg, super_arg) def_arg.forward_arg_type? && super_arg.forwarded_args_type? end
keyword_arg_same?(def_arg, super_arg)
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# File lib/rubocop/cop/style/super_arguments.rb, line 116 def keyword_arg_same?(def_arg, super_arg) return false unless def_arg.kwarg_type? || def_arg.kwoptarg_type? return false unless (pair_node = super_arg).pair_type? return false unless (sym_node = pair_node.key).sym_type? return false unless (lvar_node = pair_node.value).lvar_type? return false unless sym_node.source == lvar_node.source def_arg.name == sym_node.value end
keyword_rest_arg_same?(def_arg, super_arg)
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# File lib/rubocop/cop/style/super_arguments.rb, line 126 def keyword_rest_arg_same?(def_arg, super_arg) return false unless def_arg.kwrestarg_type? # anonymous forwarding return true if def_arg.name.nil? && super_arg.forwarded_kwrestarg_type? return false unless super_arg.kwsplat_type? return false unless (lvar_node = super_arg.children.first).lvar_type? def_arg.name == lvar_node.children.first end
positional_arg_same?(def_arg, super_arg)
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rubocop:enable Metrics/CyclomaticComplexity, Metrics/PerceivedComplexity
# File lib/rubocop/cop/style/super_arguments.rb, line 99 def positional_arg_same?(def_arg, super_arg) return false unless def_arg.arg_type? || def_arg.optarg_type? return false unless super_arg.lvar_type? def_arg.name == super_arg.children.first end
positional_rest_arg_same(def_arg, super_arg)
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# File lib/rubocop/cop/style/super_arguments.rb, line 106 def positional_rest_arg_same(def_arg, super_arg) return false unless def_arg.restarg_type? # anonymous forwarding return true if def_arg.name.nil? && super_arg.forwarded_restarg_type? return false unless super_arg.splat_type? return false unless (lvar_node = super_arg.children.first).lvar_type? def_arg.name == lvar_node.children.first end
preprocess_super_args(super_args)
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# File lib/rubocop/cop/style/super_arguments.rb, line 162 def preprocess_super_args(super_args) super_args.flat_map do |node| if node.hash_type? && !node.braces? node.children else node end end end