Typed variables in an untyped world

First, off, I’m a static type person.  Sorry, but I like me some static typing. It makes me feel warm and squishy.  It makes my IDE more useful.  I can refactor an entire code base and go to sleep and not have nightmares.

Moving on, I’ve been using Groovy for unit testing a lot lately and have decided something. I like it. Its really nice to not have to deal with exceptions and be able to create lists and maps inline.  Closures kick butt.  Its really nice and easy. However, the lack of types that enable some of the cool things bug me, but they don’t have to.

Because groovy is a dynamic language you don’t have to provide the type of any given variable. This can be good and bad. Its sometimes convenient when you don’t know or don’t care what the type of a variable is.  However, in most cases, when you do know what the variable type is, it can be helpful to put type the variable.

// untyped, but it is really an ArrayList
def someVariable = ["1","2","3"]

// same idea but now you know the type
List someList = ["1","2","3"]

Now, of course, you could have deduced the type of someVariable given its assignment, but apparently your IDE is not that smart, at least Eclipse isn’t. Especially if its one of my types and not a built in type. One of the main reasons that I type variables is that if you explicitly type them, Eclipse can do auto completion on the method names of your variable.  If you use def to declare your variable Eclipse only gives you the default GroovyObject methods.  Not the best.

Also, providing types with method signatures makes it FAR FAR FAR more obvious what you are expecting of your caller.

Consider a method with the signature:

def someMethod(def thing1, def thing2, def thing3){
...
}

Mmmmmmyeah. I have no idea what to pass to that thing. I also don’t know what its going to give back to me.

Don’t get me wrong, there are times when you don’t know some of these things or its more convenient not to declare them statically, but I have found that if you actually know at compile time what something is going to be, you may want to grease back your hair with your back pocket comb in your black leather jacket and stick it to the man with a quick def, but you from two weeks in the future and the next guy to read your code will be much happier if you throw a few types in there.