Question: is there a version of when() that binds ...

# announcements

[Patrick Ramsey]

Question: is there a version of when() that binds its argument? It’d be handy to be able to do, e.g.,

when (someFunctionCall()) { 
    Success -> it.value
    Error -> { ... error handling code ... }
}

Right now I’m just explicitly declaring a new variable in the when () clause:

when (val result = someFunctionCall()) { ... }

which works, but feels like cheating. Is this the actual accepted pattern, or is there a better way?

[Zach Klippenstein (he/him) [MOD]]

it’s just just the accepted pattern, it’s how the language is designed to be used

[Patrick Ramsey]

okay! Cool beans, was a dumb question 😆

[Patrick Ramsey]

thanks.

[ephemient]

the design: https://github.com/Kotlin/KEEP/blob/master/proposals/val-in-when-subject.md

[Patrick Ramsey]

thanks!

[Orhan Tozan]

I like to use .let { when(it) { } }

[Patrick Ramsey]

I was doing that for a while, but the extra level of indentation started to bug me

[Patrick Ramsey]

but that’s valid too!

[Nir]

if you're already doing .let then you can use if

[Nir]

and then you end up with two levels of indentation either way

[Patrick Ramsey]

yes, fair!

[Nir]

so I guess you can choose based on whether if or when is more natural, but .let { when(it) seems unnecessary

[Patrick Ramsey]

indeedy

[Patrick Ramsey]

and it looks like when (val result = …. ) is a blessed pattern, which I’m more than fine with! Just wanted to make sure