class RuboCop::Cop::Style::RedundantSelf
Checks for redundant uses of ‘self`.
The usage of ‘self` is only needed when:
-
Sending a message to same object with zero arguments in presence of a method name clash with an argument or a local variable.
-
Calling an attribute writer to prevent a local variable assignment.
Note, with using explicit self you can only send messages with public or protected scope, you cannot send private messages this way.
Note we allow uses of ‘self` with operators because it would be awkward otherwise. Also allows the use of `self.it` without arguments in blocks, as in `0.times { self.it }`, following `Lint/ItWithoutArgumentsInBlock` cop.
@example
# bad def foo(bar) self.baz end # good def foo(bar) self.bar # Resolves name clash with the argument. end def foo bar = 1 self.bar # Resolves name clash with the local variable. end def foo %w[x y z].select do |bar| self.bar == bar # Resolves name clash with argument of the block. end end
Constants
- KERNEL_METHODS
- KEYWORDS
- MSG
Public Class Methods
# File lib/rubocop/cop/style/redundant_self.rb, line 56 def self.autocorrect_incompatible_with [ColonMethodCall, Layout::DotPosition] end
RuboCop::Cop::Base::new
# File lib/rubocop/cop/style/redundant_self.rb, line 60 def initialize(config = nil, options = nil) super @allowed_send_nodes = [] @local_variables_scopes = Hash.new { |hash, key| hash[key] = [] }.compare_by_identity end
Public Instance Methods
# File lib/rubocop/cop/style/redundant_self.rb, line 86 def on_args(node) node.children.each { |arg| on_argument(arg) } end
# File lib/rubocop/cop/style/redundant_self.rb, line 120 def on_block(node) add_scope(node, @local_variables_scopes[node]) end
# File lib/rubocop/cop/style/redundant_self.rb, line 90 def on_blockarg(node) on_argument(node) end
Using self.x to distinguish from local variable x
# File lib/rubocop/cop/style/redundant_self.rb, line 81 def on_def(node) add_scope(node) end
# File lib/rubocop/cop/style/redundant_self.rb, line 126 def on_if(node) # Allow conditional nodes to use `self` in the condition if that variable # name is used in an `lvasgn` or `masgn` within the `if`. node.child_nodes.each do |child_node| lhs, _rhs = *child_node if child_node.lvasgn_type? add_lhs_to_local_variables_scopes(node.condition, lhs) elsif child_node.masgn_type? add_masgn_lhs_variables(node.condition, lhs) end end end
# File lib/rubocop/cop/style/redundant_self.rb, line 104 def on_in_pattern(node) add_match_var_scopes(node) end
# File lib/rubocop/cop/style/redundant_self.rb, line 99 def on_lvasgn(node) lhs, rhs = *node add_lhs_to_local_variables_scopes(rhs, lhs) end
# File lib/rubocop/cop/style/redundant_self.rb, line 94 def on_masgn(node) lhs, rhs = *node add_masgn_lhs_variables(rhs, lhs) end
# File lib/rubocop/cop/style/redundant_self.rb, line 74 def on_op_asgn(node) lhs, _op, _rhs = *node allow_self(lhs) end
Assignment of self.x
# File lib/rubocop/cop/style/redundant_self.rb, line 68 def on_or_asgn(node) lhs, _rhs = *node allow_self(lhs) end
# File lib/rubocop/cop/style/redundant_self.rb, line 108 def on_send(node) return unless node.self_receiver? && regular_method_call?(node) return if node.parent&.mlhs_type? return if allowed_send_node?(node) return if it_method_in_block?(node) add_offense(node.receiver) do |corrector| corrector.remove(node.receiver) corrector.remove(node.loc.dot) end end
Private Instance Methods
# File lib/rubocop/cop/style/redundant_self.rb, line 196 def add_lhs_to_local_variables_scopes(rhs, lhs) if rhs&.send_type? && !rhs.arguments.empty? rhs.arguments.each { |argument| @local_variables_scopes[argument] << lhs } else @local_variables_scopes[rhs] << lhs end end
# File lib/rubocop/cop/style/redundant_self.rb, line 204 def add_masgn_lhs_variables(rhs, lhs) lhs.children.each do |child| add_lhs_to_local_variables_scopes(rhs, child.to_a.first) end end
# File lib/rubocop/cop/style/redundant_self.rb, line 210 def add_match_var_scopes(in_pattern_node) in_pattern_node.each_descendant(:match_var) do |match_var_node| @local_variables_scopes[in_pattern_node] << match_var_node.children.first end end
# File lib/rubocop/cop/style/redundant_self.rb, line 144 def add_scope(node, local_variables = []) node.each_descendant do |child_node| @local_variables_scopes[child_node] = local_variables end end
# File lib/rubocop/cop/style/redundant_self.rb, line 190 def allow_self(node) return unless node.send_type? && node.self_receiver? @allowed_send_nodes << node end
# File lib/rubocop/cop/style/redundant_self.rb, line 150 def allowed_send_node?(node) @allowed_send_nodes.include?(node) || @local_variables_scopes[node].include?(node.method_name) || node.each_ancestor.any? do |ancestor| @local_variables_scopes[ancestor].include?(node.method_name) end || KERNEL_METHODS.include?(node.method_name) end
Respects ‘Lint/ItWithoutArgumentsInBlock` cop and the following Ruby 3.3’s warning:
$ ruby -e ‘0.times { begin; it; end }’ -e:1: warning: ‘it` calls without arguments will refer to the first block param in Ruby 3.4; use it() or self.it
# File lib/rubocop/cop/style/redundant_self.rb, line 165 def it_method_in_block?(node) return false unless node.method?(:it) return false unless (block_node = node.each_ancestor(:block).first) return false unless block_node.arguments.empty_and_without_delimiters? node.arguments.empty? && !node.block_literal? end
# File lib/rubocop/cop/style/redundant_self.rb, line 181 def on_argument(node) if node.mlhs_type? on_args(node) else name, = *node @local_variables_scopes[node] << name end end
# File lib/rubocop/cop/style/redundant_self.rb, line 173 def regular_method_call?(node) !(node.operator_method? || KEYWORDS.include?(node.method_name) || node.camel_case_method? || node.setter_method? || node.implicit_call?) end