Hi everyone, glad to be here. I am trying to creat...

# getting-started

[Smorg]

Hi everyone, glad to be here. I am trying to create an extension property, but I want to avoid creating the object that the getter returns every time I am accessing the property. Does anyone have an idea how I can implement that please?

[Shawn]

you could maybe assign it as a top-level val and then return it as the result of the get()

[Shawn]

private val _foo = Foo()

val OtherType.foo: Foo
  get() = _foo

[Smorg]

thanks @Shawn; that should work; but the object I am trying to create requires another property from the class (or object) on which I am creating the extension

[Shawn]

if the property this object depends upon is on the instance of a class, then it doesn’t make sense to have a “static” object that depends upon that property

[Shawn]

and you’ll have to instantiate a new one of these objects with each instance of the class you’re extending

[serebit]

it wouldn’t be idiomatic, but you could keep a private MutableMap with the class instance as the key and the property as the value

[serebit]

if the property doesn’t exist for a given instance, create it and store it, otherwise get it from the map

[Shawn]

maybe I’m misunderstanding the problem, but how would you access the private map from an extension val?

[Shawn]

it doesn’t seem like something you’d want to expose with a public getter, even if returned as a Map rather than a MutableMap

[Shawn]

but I could be wrong ¯\_(ツ)_/¯

[Smorg]

Thanks guys @Shawn @serebit. I probably should just move the property to the class instead.

[serebit]

@Shawn

private val map = mutableMapOf<Int>().withDefault { 0 }

val Foo.bar get() = map[this]

[Shawn]

I don’t think that’ll work since map is private within Foo

[Shawn]

oh, I see, as like a separate top-level map

[serebit]

yeah