…surprises!
Following on from my earlier posting extolling the virtues of Groovy’s ‘with’ closure.
This bit me a while back…
Groovy’s Object.with(closure) method doesn’t constitute a ’scope’ and in fact global variables actually shadow the object instance ones.
Consider this script
// file: with.groovy
class X {
def x
def y
def a
def b
}
static main(args) {
def x = 99
def y = 88
new X(x: 42, y: 21, a: 0, b: 0).with {
println "x: $x, y: $y, a: $a, b: $b"
println "x: $it.x, y: $it.y, a: $it.a, b: $it.b"
}
}
main(args)
// end with.groovy
Execution in GroovyConsole gives:
x: 99, y: 88, a: 0, b: 0 x: 42, y: 21, a: 0, b: 0
Note how on the first println $x is resolved to the global ‘x’, and so on.
It’s not really a bug…in hindsight it makes sense (as is the way with hindsight ;-)).
It is REALLY (UNpleasantly) surprising when one comes across this issue intially, however.
The tip for novice players is: always use the with closure’s parameter to access fields. Always.
