arnvald / simple_configuration Goto Github PK

just a guess

The reason is -- nil is a valid value that someone might want to set for a configuration attribute. If we tested for nil, we would not be able to tell these two scenarios apart:

MyApp.configure do
  app_id nil # expectation: assigns nil
  app_id     # expectation: returns current value
end

That blank object stored in MISSING_VALUE is only ever going to be equal to itself, so this way we can be certain that nobody is going to pass it into our method and cause an unintended read instead of a write.

fyi: my answer is copied elsewhere :D