class RuboCop::Cop::Style::ClassEqualityComparison
Enforces the use of ‘Object#instance_of?` instead of class comparison for equality. `==`, `equal?`, and `eql?` custom method definitions are allowed by default. These are customizable with `AllowedMethods` option.
@safety
This cop's autocorrection is unsafe because there is no guarantee that the constant `Foo` exists when autocorrecting `var.class.name == 'Foo'` to `var.instance_of?(Foo)`.
@example
# bad var.class == Date var.class.equal?(Date) var.class.eql?(Date) var.class.name == 'Date' # good var.instance_of?(Date)
@example AllowedMethods: [‘==’, ‘equal?’, ‘eql?’] (default)
# good def ==(other) self.class == other.class && name == other.name end def equal?(other) self.class.equal?(other.class) && name.equal?(other.name) end def eql?(other) self.class.eql?(other.class) && name.eql?(other.name) end
@example AllowedPatterns: [] (default)
# bad def eq(other) self.class.eq(other.class) && name.eq(other.name) end
@example AllowedPatterns: [‘eq’]
# good def eq(other) self.class.eq(other.class) && name.eq(other.name) end
Constants
- CLASS_NAME_METHODS
- MSG
- RESTRICT_ON_SEND
Public Instance Methods
Source
# File lib/rubocop/cop/style/class_equality_comparison.rb, line 70 def on_send(node) def_node = node.each_ancestor(:any_def).first return if def_node && (allowed_method?(def_node.method_name) || matches_allowed_pattern?(def_node.method_name)) class_comparison_candidate?(node) do |receiver_node, class_node| return if class_node.dstr_type? range = offense_range(receiver_node, node) class_argument = (class_name = class_name(class_node, node)) ? "(#{class_name})" : '' add_offense(range, message: format(MSG, class_argument: class_argument)) do |corrector| next unless class_name corrector.replace(range, "instance_of?#{class_argument}") end end end
Private Instance Methods
Source
# File lib/rubocop/cop/style/class_equality_comparison.rb, line 92 def class_name(class_node, node) if class_name_method?(node.children.first.method_name) if (receiver = class_node.receiver) && class_name_method?(class_node.method_name) return receiver.source end if class_node.str_type? value = trim_string_quotes(class_node) value.prepend('::') if require_cbase?(class_node) return value elsif unable_to_determine_type?(class_node) # When a variable or return value of a method is used, it returns nil # because the type is not known and cannot be suggested. return end end class_node.source end
Source
# File lib/rubocop/cop/style/class_equality_comparison.rb, line 112 def class_name_method?(method_name) CLASS_NAME_METHODS.include?(method_name) end
Source
# File lib/rubocop/cop/style/class_equality_comparison.rb, line 128 def offense_range(receiver_node, node) range_between(receiver_node.loc.selector.begin_pos, node.source_range.end_pos) end
Source
# File lib/rubocop/cop/style/class_equality_comparison.rb, line 116 def require_cbase?(class_node) class_node.each_ancestor(:class, :module).any? end
Source
# File lib/rubocop/cop/style/class_equality_comparison.rb, line 124 def trim_string_quotes(class_node) class_node.source.delete('"').delete("'") end
Source
# File lib/rubocop/cop/style/class_equality_comparison.rb, line 120 def unable_to_determine_type?(class_node) class_node.variable? || class_node.call_type? end