What would be the return type of this method in groovy?

Question

I have a method such as this:

def getInformation ()  {

  return [true, "reason why"]
}

which I'm using like this

def (isClear, reason) = getInformation()

Is there way to define a return type for this method so its better to read when someone is going through the method?

Answer 1

The real return type of this method is Object, since you declared it using 'def'. This means it can return anything, regardless of the object you're actually returning.

The following code would be just as valid:

def getInformation ()  {    
  return "this is some information"
}

or

def getInformation ()  {    
  return 42
}

But the returntype of the method hasn't changed.

The real question here is: why would you choose such an approach? In my opinion, the following would make things so much more clear:

Result getInformation() {
     return new Result(success: true, reason: "why")
}

This would make it much more clear to the caller, and the only thing you'd need to create is a trivial class:

class Result {
     boolean success
     String reason
}

Now you've got a clearly defined API. I would never use def in a method signature, because of the problem you're facing here.