I have recently come across a Scala class in my project which has parameters like currying. For Example:
class A (a:Int,b:Int)(c:Int){
/**
Some definition
**/
}
What is the advantage of these kind of parameterization?
When I create an object as
val obj = new A(10,20)
I am getting runtime error.
Can anyone explain?
What is the advantage of these kind of parameterization?
I can think of two possible advantages:
You can construct part of the instance in one area of the code base...
val almostA = new A(10, 20)(_)
...and complete it in a different area of the code.
val realA = almostA(30)
Your example doesn't do this, but a curried parameter can reference an earlier parameter.
class A (a:Int,b:Int)(c:Int = a){ . . .
When I create an object as
val obj = new A(10,20)I am getting runtime error.
You should be getting a compile-time error. You either have to complete the constructor parameters, new A(10,20)(30), or you have to leave a placeholder, new A(10,20)(_). You can leave the 2nd parameter group off only if it has a default value (see #2 above).
val almostA = new A(10, 20, _). It's more relevant for methods where currying can simplify syntax.
almostA = new A(10, 20, _:Int)
aandbbut don't yet knowc, it may be beneficial to partially-build an instance ofA, that can be given to something that can finish the job