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kotlinlang

how can i do 
```dataList?.size+1 ?: 0```

basically, if datalist isnt null, return its size+1. else, 0

`val size: Int = list?.let { it.size + 1 } ?: 0`

Does that really have much benefit over an `if/else`?

Is there any kind of performance penalty with the extra lambda there?

i don’t know what the bytecode becomes. if worried, if/else would work too

`val size: Int = if (list == null) 0 else list.size + 1`

Shouldn’t be much of one, `let` is inline.

```
val size = list?.size?.plus(1) ?: 0
```
:thinking_face:

better in a thread than spamming <#C0922A726|general> I guess

<@U0C2CG716> lol. ya thought of that (for a workaround) but it is not clean

<@U74HWEPTP> that would check if size is null

would it not essentially do what the `size?.let` block does?

I think Shawn’s last suggestion is probably the best, I think using `let` is probably worse than just using `if/else`

if you wanna be even more clever about it, perhaps
```
dataList?.size?.inc() ?: 0
```
but I’m not sure how that works with r/o properties

`dataList?.size?.inc() ?: 0` will also check if size == null, then return 0. else inc().

but size can never be null. so elvis operator is useless here

Size can definitely be null, `?.` doesn’t short-circuit the statement if there’s a null value (unlike C#)

<https://kotlinlang.org/docs/reference/null-safety.html#safe-calls>
the copy seems to kinda imply it does just short-circuit if it is null, but maybe that’s just me reading it a bit over eagerly

could you give me a case where size can be null

if `dataList` is null then `dataList?.size` will evaluate to null.

if `dataList` is `null`, `null?.size` would also be null

Oh, I guess I should clarify, after poking at `?.` for a few minutes, it doesn’t call methods if the receiver is null, but it will continue to traverse the statement, which is a bit more nuanced behavior.

<@U0C2CG716> ahh, gotcha. good to know :+1:

this is my test statement `dataList?.size?.let { println("First") }.let { println("Second") }` it prints “First\n Second” if dataList is null, otherwise just “Second” (because the second let statement doesn’t use `?.`

but be aware of the fact that if the lambda of `let` returns `null`, the elvis part will still be called

try: `""Hello World"?.let { println("Not null"); return@let null } ?: println("Its null :(")`