Because people keep pinging me on twitter about this, I feel like I ought to explain a bit more.

What's going on in the pattern described is that you're getting a `BazWidget1` object from the `foo` module. Then, you're passing that object you got from `foo` into `bar`, which passes it to `Baz2Flummox(BazWidget2 widget)`.

Why are you flummoxing widgets that you don't know the origin of?

What kind of program needs to mutate state on a object, by passing it from one object-mutator to another? Why do you not have clearly defined ownership of objects, and clearly defined functions that take arguments and return values?

"Inappropriate Intimacy" is a code smell where one class is delving into the inner workings of another, depending on things that ought to be private. The `BazWidget` should be a private implementation detail of `foo` and `bar`, but instead, we are passing this implementation detail from one function call to another.

More specifically, we have `BazWidget1` and `BazWidget2` objects being used interchangeably. It's tempting to blame this on the package manager or module system, but it is just a badly designed program.

This is one class of errors that a "strongly" typed language can often detect and prevent at design time. However, I've seen C++ and Java programs with the same problematic antipattern, just with more layers of Interface wrapping. And, whatever, JavaScript is what it is, and is not "strongly" typed. It lets you pass any value as any argument to any function, and leaves it up to the callee to decide what to do with it.

Personally, I have no strongly held opinion about who's best to handle this responsibility: the compiler, the caller, or the callee. There are benefits to "loosely" typed languages as well, and I'd rather not make this about that.

I've referred to this sort of thing as a "gumby baton". You're passing an object from one worker to another, and each one mutates it a little bit, like runners in a relay race where the baton is made of clay, so it gets the finger print of each worker in turn.

This is a terrible antipattern! This is how we end up with middleware depending on other middleware having been executed in exactly the right order. It is terrible for reasoning about program behavior, and results in unexpected behavior when workers are combined in novel ways. Making programs harder to reason about makes security virtually impossible, and increases the cost of maintenance and re-use. Even up front, it is a challenging pattern to use in building an application, though it sounds appealing in principle if you've never been handed a warped and mangled baton.

So, when I say "Doc, it hurts when I do this", I'm implying that the proper response is "Don't do that".

Ultimately, it's not the compiler's fault. Gumby batons exist in C++ and Java and C and are even possible in pure functional languages. Be on the lookout for it. The compiler won't protect you. The module system won't protect you. You have to use your human brain.

Another caveat just to avoid any "tu quoque" responses: I've made this mistake (and sworn to never do it again!) many times. The most egregious offender in Node is mutating the req and res objects. But, it can be very subtle and hard to spot in the initial design. We just fixed a bunch of really subtle bugs in the lockfile module by changing how it was handling the options object, because it had taken on a gumby-baton behavior internally.