This is a troublesome violation of type safety in my project, so I'm looking for a way to disable it. It seems that if a function takes an AnyRef (or a java.lang.Object), you can call the function with any combination of parameters, and Scala will coalesce the parameters into a Tuple object and invoke the function.
In my case the function isn't expecting a Tuple, and fails at runtime. I would expect this situation to be caught at compile time.
object WhyTuple {
def main(args: Array[String]): Unit = {
fooIt("foo", "bar")
}
def fooIt(o: AnyRef) {
println(o.toString)
}
}
Output:
(foo,bar)
No implicits or Predef at play here at all -- just good old fashioned compiler magic. You can find it in the type checker. I can't locate it in the spec right now.
If you're motivated enough, you could add a -X option to the compiler prevent this.
Alternatively, you could avoid writing arity-1 methods that accept a supertype of TupleN
.
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