I’m surprised there’s no guidance on when to prefer `x?.let { ... }` to `if (x != null) { … }` in th...

# getting-started

[phldavies]

I’m surprised there’s no guidance on when to prefer x?.let { ... } to if (x != null) { … } in the coding conventions. Am I right in thinking the preference of ?.let would be when the result is used as an expression, but if (!= null) is better served for control-flow?

[Klitos Kyriacou]

I also have a general personal guidance of "prefer whichever one reads better".
In this particular case, I agree with what you said, but I also sometimes use

(very + complicated() * expression)?. let { ... }

instead of

val x = (very + complicated() * expression)
if (x != null) { ... }

Because unfortunately you can't do this (something that can be done e.g. in C++):

if ((val x = ...) != null) { doSomethingWith(x) }

[Rick Clephas]

I also have a general personal guidance of “prefer whichever one reads better”.

That’s mostly what I do as well.

You can actually do something like that with a `when`:

when (val x = a) {
    null -> { println("x is null") }
    else -> { doSomethingWith(x) }
}

[Ubi]

If x is a val then it is does not matter but if x is a var then use x?.let{} .

[Alex Cruise]

I like not having to name intermediate values so I generally prefer ?.let

[Jacob]

if your not going to use x with the let block ie x?.let{doSomethingWithoutX()} then you'd be better off just doing an if