How idiomatic is using an Immediately Invoked Function Expression (IIFE) with an Elvis after

let

,

also

,

apply

etc. to execute some code when the receiver is null? For example,

val response = getFromUrl(...)

response?.data?.user?.also {
    ...  // welcome the user, save data, and lot more.
} ?: {
    showError("Login failed")
} ()  // IIFE

Not my preference. It's unclear if it's invoked because

response?.data?.user == null

or because the

also

block returns

null

. It's also less readable than just an

if

statement, IMO. I'd do something like this, depending on what you want:

val user = response?.data?.user

if (user != null) {
   ...  // welcome the user, save data, and lot more.
} else {
  showError("Login failed")
}

@sindrenm Got it! from your first answer, the ambiguity really depends upon the Scope function that we use. For example

let

&

also

- both has different outcomes.

I would use

run

instead of

also

in your case, this is how I understand it:`if response, data and user are not null then run a bunch of things`

why do you need the function at all, why not

?: showError(...)

@christophsturm true for a single line, but for a block of code, don't we need an IIFE?

One example is

?: run { log("null"); return }

IIFE isn't a thing in kotlin, use

run {}

instead.

run

inlines, the IIFE does not, and will create a class/Function0.invoke call. Much less efficient.

I am a little curious as to who Stephan Schroeder is and what they have to do with this. 😮

@sindrenm actually I meant you only 😐 I hit enter as soon as I typed

@

🙈 and now only realized that I mentioned someone else 🤦🤦🤦 Updated now ✔️

Oh well, now they can get in on the fun, too! 🎉 Made me think of this https://kotlinlang.slack.com/archives/CJLTWPH7S/p1572635193281700?thread_ts=1572624750.257500&cid=CJLTWPH7S