Question

I started dabbling in groovy yesterday. There’s an example on the groovy website that I understand but I would like to know more about why it works the way it does. What’s confusing me is who[1..-1]. Is this like saying who[1..who.length()-1]? I can’t find any documentation on this syntax. Are there any good groovy tutorials out there besides what is on http://groovy.codehaus.org/?

class Greet {   def name   Greet(who) { name = who[0].toUpperCase() +                       who[1..-1] }   def salute() { println 'Hello $name!' } }  g = new Greet('world')  // create object g.salute()              // Output 'Hello World!' 

Answer 1

You’re right — a negative number in a range basically refers to the end of the list, rather than the beginning. -x is equivalent to who.length()-x.

What you’re dealing with is known as slices in Python. (I mention the terminology because searching for something like ‘groovy slices’ may help you find more information, although I don’t know if they’re actually called ‘slices’ in reference to Groovy.) You can find more information on this particular syntax feature here.

As for other resources, I found the book Groovy in Action to be quite handy for learning Groovy.