[vinceguidry]

You're invoking "IDE" features like it's a panacea. In reality IDEs have only a few limited ways to catch these kinds of errors. With a statically-typed language it can run static analysis at intervals and make sure that all the messages being passed are actually defined on the objects they're being passed to. You can do this precisely because that's what static types gives you.

In dynamic languages you can't do this because you don't know the type that any given identifier is pointing to. The type could be completely arbitrary, I.E. coming from external input. You might think, "oh, well you could just check against all possible methods", and you'd be right, except for Ruby. Ruby allows you to override what happens when you call an undefined method, (method_missing) letting you execute completely arbitrary code that lets undefined methods look just like methods. You could call car.start_and_drive_to_the_bank, and set up the Car type so that it can handle methods like that, (perhaps calling car.start, and then car.drive(bank)) along with .start_and_drive_to_the_mall and whatever. In practice that's bad Ruby, but you still have to be able to handle that, Bad Ruby is still Valid Ruby.

So there's just no way to tell in Ruby whether any given method call is correct or not.

I have an idea to conventionalize method_missing overrides so that they're easier to analyze. Maybe define a regular expression on the class so that the analyzer can sort out what's likely to work at runtime and which messages aren't. Not sure how well it would work until Matz manages to implement static typing as he wants to do in the future. Until you can tell whether any given identifier is likely to be of a type that overrides method_missing, you'd be running the method_missing analyzer for all types on all method calls.