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#announcements
- m
mg6maciej
03/10/2017, 4:00 PMreturn stack(*toTypedArray())➕ 2📡 1✅ 1👍 2 - m
mg6maciej
03/10/2017, 4:00 PMUse magic star operator. - d
danko9
03/10/2017, 4:01 PMand the star wins! @mg6maciej👍 1✅ 1📡 1 - d
danko9
03/10/2017, 4:01 PMthank you - d
danko9
03/10/2017, 4:04 PMthank you for solving the ungoogleable - t
tjb
03/10/2017, 4:08 PM@mg6maciej do you mind expanding on what
does? i am new to Kotlin and curious. Or perhaps can you point everyone in the right direction in the docs for this?*👍 1✅ 1📡 1 - t
tjb
03/10/2017, 4:08 PMsorry to jump into the convo! - m
mg6maciej
03/10/2017, 4:09 PMThis is called spread operator. - m
mg6maciej
03/10/2017, 4:09 PMIt's spreading list / array to `vararg`s params.👍 1✅ 1📡 1 - r
Ruckus
03/10/2017, 4:10 PM - m
mg6maciej
03/10/2017, 4:10 PMInteresting example.
. I wouldn't think of this, but it's quite useful.val list = asList(-1, 0, *a, 4)📡 1👍 1✅ 1 - d
danko9
03/10/2017, 4:11 PMwhat is a there? another list? - d
danko9
03/10/2017, 4:11 PMoh yeah, it's on the page. - m
mg6maciej
03/10/2017, 4:11 PMarray - k
kevinmost
03/10/2017, 4:11 PMif you wanted to spread a list in, you'd do*a.toTypedArray()✅ 1👍 1📡 1 - r
Ruckus
03/10/2017, 4:12 PMThis answer has some good notes: http://stackoverflow.com/a/39389045/2094298✅ 1📡 1👍 1 - m
mg6maciej
03/10/2017, 4:12 PMApparently in Kotlin you cannot use lists in that way directly. In Groovy you could. - t
tjb
03/10/2017, 4:12 PMawesome thank you all so much! ill start reading 🙂 this is another reason why i love Kotlin so much. The community is awesome at answering some of my very trivial questions 😛 - d
danko9
03/10/2017, 4:14 PMok so a basic question . . . coroutines are only useful if you have a lot of "tasks" that each spend a lot of time doing nothing, correct? - d
danko9
03/10/2017, 4:15 PMand the most common example of that would be, say, an http request? - d
danko9
03/10/2017, 4:15 PMif all your tasks are doing something, then in a simplistic way, you don't need more tasks than cpus, correct? - d
danko9
03/10/2017, 4:17 PMi think i remember reading that the whatsapp guys made very heavy use of that pattern. i think they had a coroutine for each user's websocket, so there were a ton of coroutines but usually each one was doing nothing. - d
danko9
03/10/2017, 4:17 PMat a given time very few were doing any computation that is - r
Ruckus
03/10/2017, 4:19 PMCoroutines can work really well for CPU intensive tasks if you design them properly. https://github.com/Kotlin/kotlinx.coroutines/blob/develop/ui/coroutines-guide-ui.md#blocking-operations✅ 1📡 1👍 1 - r
Ruckus
03/10/2017, 4:20 PM#coroutines is a better place to ask - r
Ruckus
03/10/2017, 4:25 PMAccording to @ilya.gorbunov:Spread operator always copies an array, so that neither the function nor its caller are required to make defensive copies of the array.
It might be possible for the compiler to optimize such copying away, for example when one vararg function passes its array to another vararg function and doesn't use it itself after, however such optimization has not been baked yet.
https://discuss.kotlinlang.org/t/hidden-allocations-when-using-vararg-and-spread-operator/1640✅ 1📡 1 - u
uli
03/10/2017, 4:47 PMIt also mentions:It looks like there's currently no way to modify elements of array passed as vararg...
- m
miha-x64
03/10/2017, 4:54 PMArray is being defensive cloned, AFAIK. - u
uli
03/10/2017, 4:54 PMwell, you only need to be defensive if there is something to defend about 😉 - u
uli
03/10/2017, 5:04 PMwell, i guess the caller could mess with the array after the call.