How would I fix this code? I’d like `reportError()...

# announcements

[Ellen Spertus]

How would I fix this code? I’d like reportError() to be called if the value preceding let is `null`:

store.state.selectedTab?.content?.url.let {
     doSomething(it)
 } ?: run {
     reportError("Unable to get URL to send")
 }

Assume that both doSomething() and reportError() are void.

[Shawn]

if you don’t need to capture that url, why not just use if/else?

[Ellen Spertus]

Oops, I oversimplified my code. I have edited it to add it.

[Anastasia Finogenova]

This code will not compile if url is nullable

[Ellen Spertus]

url isn’t nullable, but selectedTab and content are.

[Luke]

I think you want ?.let

[Shawn]

also true

[Anastasia Finogenova]

If you don't do ?.let it will not compile

[Shawn]

but also, still, if/else would work just fine here

[Ellen Spertus]

Thanks, @Luke. Could you explain why?

[Ellen Spertus]

@Shawn Wouldn’t I have to save the argument to doSomething() somewhere?

[Shawn]

you would, but imo that’s not such a big deal

[Shawn]

also, the result of a safe-navigation call is always nullable, so you’ll need to keep using ?. as you navigate through the structure

[Luke]

let is callable on nullables. store.state.selectedTab?.content?.url returns null if any call return null, in which case it is null inside let{}. run is never called

[Luke]

by adding ? before let, you don’t call it if no url can be found

[Ellen Spertus]

Thanks, @Luke.

[Alowaniak]

What's wrong with just doing

val url = store.state.slectedTab?. content?.url
if (url != null) doSomething(url) 
else reportError...

[Kroppeb]

I like

when(val url = store.state.slectedTab?. content?.url){
    null ->reportError()
    else -> doSomething(url) 
}

[Stephan Schroeder]

@Kroppeb nice work! the format looks cleaner to me (a happy coincidence that null -> and else -> line up 😃)