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kotlinlang

`val A.extVal get() = B(this)`
Is there a way to not construct `B` every time I reference to `A.extVal`? Given that I don't own class `A`.

I tried using the `lazy`-delegate, but it didn't work because you don't have access to `this` inside the function you pass to it. I guess you could create your own version of the `lazy`-delegate that passes the receiver object as a parameter to the function though.

You can read how to do this here: <https://kotlinlang.org/docs/reference/delegated-properties.html>

This kinda works, but it is not thread safe:
```
class LazyExtension&lt;V, T&gt;(val f: V.() -&gt; T) {
    data class Result&lt;T&gt;(val t: T)
    var result: Result&lt;T&gt;? = null
    
    operator fun getValue(thisRef: V, property: kotlin.reflect.KProperty&lt;*&gt;): T {
        return result?.t ?: Result(thisRef.f()).also { 
            result = it
        }.t
    }
}
```

I fixed it up a little bit so it doesn't use that `tmp` variable.

<@U1ENTFTA4> Note that this implementation of LazyExtension would return the same value for _any_ receiver after it had been initialized. Probably not what the author wanted.

Ah, that's true. You would also need to keep track of all the receivers.

I guess that could turn out to be quite a memory leak if it is used a lot.