Hi all,
I have this strange snippet of code:
def addAllOpt(kvs : K#typedTupleOpt[_]*) : Record[K] = {
kvs.foldLeft(this) { case (record, kv) => record add(kv._1, kv._2) }
After a lot of troubleshooting, I can’t figure out what this method means.
First of all: In the signature what meas the “sharp” symbol in “K#tupedTuple”? Does this have a particular syntax value?
Also, what means the symbol [_]* ? Why is ther a tar at the end of an empty type parameter?
And, finally, do exist a specific “add” function in the standard scala library? which take two parameter and just adds them?
Thank you all !
# is type projection operator
[_] is a wildcard type parameter
* is a varargs marker
Reading that all together: the type K has a member type called typedTupleOpt, which is generic, so it requires a type parameter passed inside square brackets. But if the actual type parameter if not really used, it can be replаced by a wildcard _. Finally * after the type of the method parameter means that addAllOpt method accepts not just one parameter of type K#typedTupleOpt[_] but any number of them.
record add(kv._1, kv._2) is just syntax sugar for a method call record.add(kv._1, kv._2) where the dot was skipped
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