class RSpec::Mocks::ArgumentMatchers::SingletonMatcher

Intended to be subclassed by stateless, immutable argument matchers. Provides a ‘<klass name>::INSTANCE` constant for accessing a global singleton instance of the matcher. There is no need to construct multiple instance since there is no state. It also facilities the special case logic we need for some of these matchers, by making it easy to do comparisons like: `[klass::INSTANCE] == args` rather than `args.count == 1 && klass === args.first`.

@private

# File rspec-mocks/lib/rspec/mocks/argument_matchers.rb, line 146
def self.inherited(subklass)
  subklass.const_set(:INSTANCE, subklass.send(:new))
end