I am studying CanBuildFrom, and I know that this mechanism is used to create collections that need to be returned as a result of executing the map(...) method. I want to read the source code, but I can't find it in the standard library.
Related
Rookie question here.
I have 2 apps that utilize Hazelcast, one is in Typescript and the other is in Scala.
The Typescript app stores all the data and the Scala one interacts with it.
I need an easy way to parse items inside of a map to a case class, this is easy if the HazelCast data is saved within Scala because it can be cast but when I attempt to do this with data stored from Typescript I get the following
java.lang.ClassCastException: com.hazelcast.core.HazelcastJsonValue cannot be cast to TheCaseClass
I'm using circe and finch in the rest of the application, not sure if circe can be used here to parse it.
tl;dr Is there an easy way to convert HazelCast data stored in Typescript to a Scala case class.
Thanks
You cannot just take one arbitrary class and cast it to another class. You have to parse them. If you use Hazelcast then probably Hanzelcast Scala is what you should use.
Wiki suggest that you would have to do at least:
import com.hazelcast.Scala._
serialization.Defaults.register(conf.getSerializationConfig)
though it might require you to write your own custom serialization.
I have the following declaration of a function
def myfunc(l: List[RoseTree]): Option[RoseTree] = {
//Complex calculations
}
Now, I have to run this function on two huge different lists. So, I wish to run the same function, with different data, in parallel.
I have been taking a look at the Future module of Scala.
However, I also wish that when either of the functions returns a "Some(RoseTree)", then it tells the other call to stop and keep the result. Is this possible?
Kind regards.
Scala has built-in feature for this. You can use Future in combination of Future.firstCompletedOf().
Please have a check at the Scala doc and I would suggest to have a look at this post
As point in the comments section, the Future.firstCompletedOf does not meet the requirement "cancel the futures after one is completed". You can use Monix Task (which is a replacement for Scala Futures), which support by default this. Please have a look at this.
I'm new to scala and struggling with the documentation a little bit. I was looking at a piece of code in the spark codebase (cosine similarity for RowMatrix) and saw that they use Iterator.tabulate. Not knowing what that function does I looked in the scala API docs, only to find out the function does not exist. Except that it does exist, because I can use it in the repl (hmm, maybe I'm looking at the wrong API docs version ... no, this this is the current version).
After a bit of searching I find out that tabulate is defined (at least) in scala.collection.generic.SeqFactory and scala.collection.generic.TraversableFactory. These two however appear not the be connected in the dependency graph. I can't find any path between the two, and hence no way of actually knowing - from looking at the API docs - that .tabulate even exists.
So the question is: how do you find .tabulate and it's documentation from looking at the API docs for the class (say Iterator or Seq). Do I just have to google my way around it, or is there some magic button in the scala docs that will make the thing appear?
This doesn't seem to be limited to just .tabulate but a more common issue (at least for me), looking at library code functions seem to exist that are never mentioned in the API. Another example is
org.apache.spark.mllib.linalg.distributed.RowMatrix.toBreeze
I still don't know if that function exists, some code seems to use it, but I can't find any documentation about it.
In Scala source code all logic of Iterator defined in one file Iterator.scala. Function tabulate that you're looking for is defined in object Iterator in Scala API you make search by trait Iterator so this is why you can't find it.
In right corner of doc you can switch to object iterator and here you will find Iterator$#tabulate util function.
I would like to know how to pass a variable number of arguments and types to an RPC function in UNITY?
I saw some similar questions asked in here but no straight answers on how to do it.
Thanks
RPC function is deprecated since unity 5.X cause a new network system was released. If you have an already made game and can't migrate from old network API you should take a look on Legacy Network RPC's documentation, there is good covering information about how to pass params into RPCs.
Basicaly what you need is an array of objects like:
networkView.RPC("MyMethod",RPCMode.All, arg1[], arg2, arg...);
where args must match the end point method signature MyMethod(arg1[], arg2, arg...).
If you need declare methods with variable types and number of arguments you'll have a lot of ways to proceed (from using specific objects as arguments through convert or serialize an object as byte arrays or something that you would deserializes after receive ). You can improve your research results on this approaches by searching directly on "C#" instead of "Unity" or "RPC" targets...
There are some constructs that don't have equivalents in java. Examples would be
named parameters
instance private members
Where/How does Scala store the information necessary for this stuff (some kind of flag in the first case, the parameter names in the second case?
If I get it right this has to get stored in the byte code, since it works even if I just have a compiled library without the source code!?
This information is captured in an annotation named ScalaSig in the class file (see this answer for an example).
You can view the (not very human-friendly) annotation with javap -verbose, or parse it using an internal API, but in general neither should be necessary.