I have a rudimentary question ```fun foo getData let data gt kotlinlang #getting-started

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Title

lenqnr

06/26/2019, 2:28 PM

I have a rudimentary question.

fun foo() {
    getData()?.let { data ->
        doSomething(data)
    }
}

Is it equivalent to this?

fun foo() {
    val data = getData() ?: return
    doSomething(data)
}

I don't like adding more indentations, so came up with the second one. Is it OK?

Dico

06/26/2019, 2:29 PM

Yes it does the same.

lenqnr

06/26/2019, 2:31 PM

Thank you. I've never used like this, so it looked awkward a bit.

Dico

06/26/2019, 2:33 PM

I also like this notation

val data = getData()
if (data != null) doSomething(data)

I recommend having braces for if statements always unless it's a one liner. Never do this, it is error prone (in my opinion and experience):

if (data != null)
    doSomething(data)

arekolek

06/26/2019, 2:35 PM

You could have also done

fun foo() {
    getData()?.let(::doSomething)
}

lenqnr

06/26/2019, 2:40 PM

Thank you guys. I'll give it a try if

return

is not needed.

In addition to the previous question, I wonder if this is a bad habit.

fun foo() {
    bar() ?: return
    doSomething1()
    ...
}

fun bar(): Unit? {
    try {
        doSomething2()
    }
    catch (e: SomeException) {
        return null
    }
    ...
    return Unit
}

So I can handle functions in the same way whether or not they return a value. But I'm not sure if it's fine.

dalexander

06/26/2019, 6:28 PM

Explicitly returning Unit from Kotlin code seems like it's asking for trouble. This basically re-creates the "check the return value!" issue that the C stdlib has.

Ruckus

06/26/2019, 6:30 PM

@lenqnr Why not just return a

Boolean

Then you can do

if (!bar()) return

Dico

06/26/2019, 6:36 PM

Yeah I wouldn't recommend using

Unit?

. I wonder if you can omit the last return statement

lenqnr

06/26/2019, 6:39 PM

Maybe I loved syntactic sugar too much. But

try... catch

in every functions feels a little verbose.

@Dico I can't omit it, but I can in

withContext

block. I don't know why.

Dico

06/27/2019, 12:54 AM

What

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