Scala - Create a new Class on runtime based on dynamic data - scala

Question

I have an array of String which I will be receiving from an arbitrary function. I want to use the elements of the array to create a new class at runtime (not a new object of an existing class). Let me give you an example
val keyCounts = Array[String]
def newDomainPartioner(keyCounts : Array[Strings]) : DomainPartitioner{
return class DomainPartitioner with Serializable {
def getPartition(key: Any): Int = key match {
case <first element of keyCount> =>
1
case <second element of keyCount> =>
1
case <third element of keyCount> =>
1
case <forth element of keyCount> =>
1
case _ => 0
}
}
}
Is there a way to achieve the intended functionality ?

Answer 1

You can use reflection to generate a new class at runtime, see this question for more details:
Generating a class from string and instantiating it in Scala 2.10
However, it sounds like you would be better off having a single class that encompasses the behaviour you want, and returning an instance of that class, eg:
class DomainPartitioner(keyCounts: Array[String]) with Serializable {
def getPartition(key: Any): Int = keyCounts indexOf key match {
case 1 =>
1
case 2 =>
1
case 3 =>
1
case x if myConditionIsTrue(x) =>
1
case _ => 0
}
}
def newDomainPartioner(keyCounts : Array[Strings]) =
new DomainPartitioner(keyCounts)

Answer 2

val arrayStrings: Array[String] = Array("we","are","great")
def arrayCaseClass(schema:Array[String], className:String)
:String = {
def arrayElements(element:String):String = {
val types = element
element match {
case x if !x.isEmpty => s" $element:String"
case _ => s" $element:$types"
}
}
val fieldsName = schema.map(arrayElements).mkString(",\n ")
s"""
|case class $className (
| $fieldsName
|)
""".stripMargin
}
println(arrayCaseClass(arrayStrings, "ArrayCaseClass"))