Why does the last line here trigger "Cannot query the value of this property because it has no value available"? What am I doing wrong to store a custom property via the object factory?

@JvmInline
value class ProjectVersion(val version: String)

objects.property<ProjectVersion>().set(ProjectVersion("oink"))
println(objects.property<ProjectVersion>().get().version)

You create a property instance, let's call it

foo

, and set its value to

oink

. Then you create a new property instance, let's call it

bar

, and query its value. Why do you expect

bar

to have the value you have set on

foo

?

Ah, crap, I see.

Speaking in primitives, you do

val foo = "bar"
val bar = null
assert bar == foo

🙂

But how to I read an unnamed property then via the object factory?

What do you mean by "unnamed property"? Actually my primitive example was bad, better is

"bar"
assert null == "bar"

😄

objects.property<ProjectVersion>()

gives you a property instance. You then set a value. And then you discard it. You probably meant

val foo = objects.property<ProjectVersion>().set(ProjectVersion("oink"))
println(foo.get().version)

(Besides that you of course should never call

get()

at configuration time, because that introduces the same bad race-conditions

afterEvaluate

gives you.

Assume that I cannot have

val foo

in our example. Is there no way to gets it's value from

objects

after its creation?

objects

is just a factory that creates a new property instance for you

Oh, I thought it's more like a registry of properties...

What do you actually try to achieve?

I'm looking for a way to inject a custom type into the constructor of a custom task. It has to be the constructor I'm injecting to, not a property of the task.

So? Just give it as argument to the

register

call

Now we're back to square one: I want to use replace instead of register 😉 I know, you suggested to remove and then register, but I'd really like to avoid that.

So you tried to not inject the value to the constructor, but to retrieve it within the constructor body or what?

Yeah, I was considering to use a build service. But that's really becoming too complex for something that should be very simple to achieve 😞

Well, replacing a task that is already registered is faaar from being simple and shouldn't be done :-)

what are the tasks in question and how do they differ in behavior?

If it shouldn't be done, why is there a public API for it? But don't get me started on that... IMO Gradle is recently doing a very bad job at making clear what APIs (or better: practices) to use, and what not. All convenient API seems to be discouraged, and all recommended API lacks functionality. With Gradle becoming more and more declarative also, I'm seriously considering to just to back to Maven 😅

Probably backwards compatibility. Regarding practices, they just launched a yet-to-grow best-practices chapter in the docs

I generally find when asking question here it's best to start at as a high a level as possible since you may have walked down a bad path to get to your current problem.

Well, the problem is backwards compatibility. You don't want to constantly break every build and plugin on every major version just to evolve the API

Well, I've been attending the talk about Maven 4 at JavaLand, and was quite pleased with the evolution, I have to say.