I don’t see the pain personally

changing the signatures will be a breaking change

Yes definitely, if it gets fixed, it will be new functions

orNull

yes of course

I am talking about porting

Integer.parseInt

to Kotlin (that's the only way)

Guys, can you explain me the situation (and the reasoning behind it)? It turned out that there are no ways to

clone

collections:

mapOf(1 to 2) //?
setOf(1) //?

listOf(1).toList() //ok

// two of them!
arrayOf(1).copyOf()
arrayOf(1).clone()

DataClass(1).copy()

The only workaround I've found is

HashMap(mapOf(1 to 2))
 HashSet(setOf(1))
 ArrayList(listOf(1))

but it is only for mutable collections

Try toList()/toSet()/toMutableList()/toMutableSet()

@konsoletyper: ok, that works, except for

toMap()

apparently it needs

Iterable<Pair<, >>

, which would be very inefficient

i think these functions are missing:

<K, V> Iterable<Map.Entry<K, V>>.toMap(): Map<K, V>

and

<K, V> Map<K, V>.toMap(): Map<K, V>

anyway, can you explain me why there is no universal way to clone a structure? Like a

clone

function for every container (extension function?)

You can create a copy of the map with

HashMap(map)

know that. But it needs casting back to

Map

not a pretty solution

@voddan: I don’t quite understand the “why” form of question. Why there is no human settlement on the moon?

@orangy: ok, how about this: Don't you think it would be useful to have a unified method on all collections to clone them? If not, what are the cons?

@voddan:

.toList().toMap()

should work fine. I agree, it's slightly less efficient comparing to direct copying of a map, but not "very inefficient". Benchmarks are welcome

@konsoletyper: fair enough. Benchmarks are not that stable , the difference jumps from x2 to x3, but it is certainly not "slightly less efficient "

-.txt

@voddan: now run

map.toList().toMap()

after

HashMap

and see the difference. Don't forget HotSpot needs some time to warm up.

my bad. I repeated all operations for 2 times:

tolist_tomap: 1000 rounds 818361095 ns, 818361 per round

time_hashmap: 1000 rounds 508941933 ns, 508941 per round

tolist_tomap_2: 1000 rounds 369167544 ns, 369167 per round

time_hashmap_2: 1000 rounds 183737713 ns, 183737 per round

now the difference is close to x2, but still no good

results are stable

I am doing this on desktop, not sure what would it be on android

oddly enough,

clone

method exists on all java collections, but to use it from cotlin you have to go under the interfaces

Map

or

MutableMap

@voddan: https://youtrack.jetbrains.com/issues then

thanks for reviewing!

BTW, HashMap.clone must be faster than HashMap(Map) constructor

@konsoletyper: should I create an issue for clonning all collections, or just for Maps?