Take the following controller:
package test
class TestController {
static defaultAction = "test"
def test() {
render "test"
}
}
Why is test
defined with def test() {
instead of something like void test() {
? Isn't the def
keyword only used for closures or functions in a script (i.e. not in a Groovy class)?
render
is void so in this case the test
action could be void
, but in the case where you return a model map the action has to be non-void:
def create() {
[personInstance: new Person(params)]
}
Since some actions can return a value and some don't, the general syntax has to return def
to support all variants.
Burt's answer is correct but the real problem I was having is that I misunderstood what def
is. Rather than being like var
in JavaScript, you can think of it like Object
in Java.
I thought that using def
was like doing (JavaScript)
var test = function() {
alert("test");
}
while in reality it's just like (Java)
public Object test() {
return someObject;
}
It's not a different kind of function/closure, it's like a return type—def
can be applied to any object (Groovy has no data primitives, so any value is also an object, unlike in Java).
It helps my Java brain to think of
def bar = "foo";
as
Object bar = "foo";
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