GPath spread operator (*.) and another GinA example

[Kristian Jones]

Hello again.
I'm slowly getting there with groovy and working through the example listings in GinA but this time I think I really have found an example that doesn't work with the latest version.

Listing : 7.23

class Invoice
{
 List items
  Date date
}

class LineItem{
  Product product
  int count
  int total(){
    return product.dollar * count
  }
}

class Product {
  String name
  def dollar
}

def ulcDate  = new Date(107,0,1)

def ulc = new Product(dollar:1499, name:'ULC')
def ve = new Product(dollar:499, name:'Visual Editor')

def invoices = [ new Invoice( date:ulcDate
                              ,items:[ new LineItem(count:5, product:ulc )
                                      ,new LineItem(count:1, product:ve ) ]
                            )
                ,new Invoice(date:[107,1,2]
                             ,items:[ new LineItem(count:4, product:ve ) ]
                            )
                ]
assert [5*1499, 499, 4*499] == invoices.items*.total()

I'm guessing this doesn't work because GinA assumes 1.0 and I'm on 1.6.5.

I found this bug http://jira.codehaus.org/browse/GROOVY-2387 which recommends replacing the last line with

assert [5*1499, 499, 4*499] == invoices.items.sum()*.total()

An obvious question is where did sum() come from?

Can anyone explain how I should be using spread (*.) operator in the later version of groovy as it seems like a really powerful feature

My final question is, are there many of these gotchas in the groovy GDK which newbies should be aware of ?

Kris

[Kristian Jones]

Found the following on the authors website : http://www.manning-sandbox.com/thread.jspa?threadID=33351&tstart=0

.flattern() works too.

[Dave Klein]

sum() is a method on Collection after it's been enhanced by the GDK. It was there in 1.0 but new over-ridden versions were included in 1.5 and above. You can read more about it and find many other hiddend Groovy nuggets in the GDK docs: http://groovy.codehaus.org/groovy-jdk. This doc will show you all the nifty features added to JDK classes / interfaces.

Have fun!
Dave