Hi,
Since we are now considering Groovy 2 for Gradle 2, I wanted to throw
this into the conversation…
One of the great additions to Groovy 2.2 was implicit closure coercion
for Single Abstract Method types. In 2.3 this gets better with closure
param type inference. This means you can do the following…
// Setup…
interface Action<T> {
void execute(T thing)
}
class Thing {
String name
}
class ThingConfigurer {
Thing thing
void conf(Action<Thing> action) {
action.execute(thing)
}
}
def t = new Thing()
def tc = new ThingConfigurer(thing: t)
// The point…
tc.conf {
it.name = "foo"
}
assert t.name == "foo"
That is, closures are implicitly converted to types. This works if the
SAM has a return type and even for multiple params (and generics are
inferred).
This would be great for us because it means we don't have to generate
overloads at runtime and IDEA at least understands these closure
coercion rules really well where as it does not understand our runtime
overloads. I say “would” because it doesn't quite match our pattern of
making the param the delegate in the Action case.
I think we can still get some benefit out of this for other cases (e.g.
Test#beforeTest), but I can't find any way to leverage this and avoid
our runtime generated overloads because of the delegate issue. It's a shame.
The end result, is that we could potentially drop Closure from our API
completely for Gradle 2 without forcing users to change their
buildscripts. In the Closure usages that aren't actually used for
configure-by-closure (e.g. Test#beforeTest) would could replace with
real types.
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