Would be great foo bar kotlinlang #announcements

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Title

l

liminal

06/11/2017, 10:48 PM

Would be great, foo bar

r

redrield

06/11/2017, 10:48 PM

liminal: basically,

in

and

out

tell the compiler whether your function or class produces a generic, or consumes it

If you have this:

fun <T> hello(): T { }

, you'll be told that T can be marked

out

Because

hello()

doesn't consume, or have any parameters of type T

It just produces an instance of T

Flip side,

fun <T> hello(thing: T): String { }

, you'll be told T can be marked

in

You consume, or take a parameter of type T

And don't produce it

Something in the middle wouldn't need variance at all, because it produces and consumes

fun <T> hello(inst: T): T { }

is an example of that

l

liminal

06/11/2017, 10:51 PM

I see. Thanks!

t

tapchicoma

06/12/2017, 7:00 AM

nice explanation, thanks!

a

azabost

06/12/2017, 10:01 AM

@redrield Could you please also explain what do you gain by marking the variance? Is it important for some reason?

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