hi all i have a question regarding best practice, ...

# announcements

[Nir Golan]

hi all
i have a question regarding best practice, memory, and everything you can share on the subject
private var lateinit xyz
private var xyz : ABC ?= null

what is better?

[gildor]

same for memory

[gildor]

choice between of nullable/lateinit is depends on your case, not on performance

[Nir Golan]

thanks

[diesieben07]

One big difference is that a nullable property can be set to null again by you or some other code.
lateinit is designed for things that are initialized once

[gildor]

if nullable is fine for you (so it doesn’t cause too many unnecessary null checks) I would use nullable

[gildor]

even tho it’s possible to check if lateinit is initialized, but I believe that if you have such case better to use nullable

[Nir Golan]

does isInitialized cost more then null checks?

[diesieben07]

No, it's a compiler intrinsic that just does a null check

[gildor]

Why I don’t recommend this, is that if you have 1 case, it may require in future 2 cases, so it become not safe to use, but nullable field is always save, compiler will check it for you, not your runtime

[diesieben07]

Yes, lateinit is a kludge for using frameworks that do "magic field injection", often based on annotations.

[Miguel A. Ruiz]

If you only need to initialize the variable the first time and you don't need change it more, maybe you can use an immutable approach: private val xyz: ABC by lazy {}.

[Nir Golan]

thats something we didn't thought on

[Nir Golan]

thanks

[Miguel A. Ruiz]

you are welcome

[Ruslan Demyanov]

Is it any analog of let function for lateinit property or just if isInitialized check? Or maybe some extension for it?

[diesieben07]

If you need isInitialized you probably want a nullable property instead.

[diesieben07]

The only way to check is indeed isInitialized for lateinit. What's your use-case?

[Ruslan Demyanov]

I thought about creating an extension function for lateinit property, but did not have enough knowledge to implement it.
The basic idea is to use a function like the var?.let{} function, but with lateinit check

[diesieben07]

That's not possible, since the type system has no idea about the lateinit status of the property.

[diesieben07]

You should just use a nullable property, that's what they exist for.

[Ruslan Demyanov]

Thanks for explanation