Hi, is there a difference between those 2 options here: ```fun main() { var text: String? = "hel...

# android

[Remon Shehata]

Hi, is there a difference between those 2 options here:

fun main() {
    var text: String? = "hello"
    text?.let { 
        print(text) // option 1
        print(it) // option 2
    }
}

[Marko Novakovic]

yes there is
it is encapsulated in let block which means that no matter if text change it will be the same as when you called .let. text is not safe to use like that

[Max Ferrier]

Both will work, but it represents the value you have tested and is safe. Your text variable is a var, so it can be modify elsewhere and crash while you use it.

[Marko Novakovic]

and text is still nullable inside let

[Remon Shehata]

Thanks Marko.

[Marko Novakovic]

you’re welcome

[Vampire]

How can text change? let is not executed asynchronously

[Alex]

text might have been changed in another thread, no? You can not be sure it didn't

[Vampire]

If it is multi-threaded and some other thread might change text.
In the example, both options are imho absolutely identical.

[Alex]

It would be nice to clarify this to Remon, right? Even if the example given will not run into this problem. Just leave out the fun main() parts and the multithreading problem cannot be excluded anymore.

[Vampire]

We just did, didn't we? 🙂

[Vampire]

As posted it is the same, if text can change asynchronously, it might not be.

[Remon Shehata]

Thanks guys, I knew that it’s not thread safe. but it’s nice to say that here so if anyone else reads the chat thread they would know.

[eygraber]

I'm 99% sure this isn't true, and that text would be smart cast to not null.

I believe the reason is because the scope of text wouldn't allow anyone to modify it before that block is run.

I think Kotlin does analysis to determine if it is captured in a scope that could modify it in another thread, and if it isn't then it does the smart cast.

https://kotlinlang.slack.com/archives/C0B8M7BUY/p1641204754087000?thread_ts=1641204105.086400&cid=C0B8M7BUY

[Vampire]

Here the missing percent 🙂

[Daniel B Duval]

You'd want to use it as a general convention.

If you expand this to an object where you use a getter for a value, the compile will fail due to not being able to smart cast. This will lead to a lot of extra boiler plate and/or null checks the let got you.

[gildor]

I would also recommend to use #getting-started channel for those questions, it’s not related on Android specifically