I declared a variable outside the function like this:
var s: Int = 0
passed it such as this:
def function(s: Int): Boolean={
s += 1
return true
}
but the error lines wont go away under the "s +=" for the life of me. I tried everything. I am new to Scala btw.
First of all, I will repeat my words of caution: solution below is both obscure and inefficient, if it possible try to stick with values.
implicit class MutableInt(var value: Int) {
def inc() = { value+=1 }
}
def function(s: MutableInt): Boolean={
s.inc() // parentheses here to denote that method has side effects
return true
}
And here is code in action:
scala> val x: MutableInt = 0
x: MutableInt = MutableInt@44e70ff
scala> function(x)
res0: Boolean = true
scala> x.value
res1: Int = 1
If you just want continuously increasing integers, you can use a Stream.
val numberStream = Stream.iterate(0)(_ + 1).iterator
That creates an iterator over a never-ending stream of number, starting at zero. Then, to get the next number, call
val number: Int = numberStream.next
I have also just started using Scala this was my work around.
var s: Int = 0
def function(s: Int): Boolean={
var newS = s
newS = newS + 1
s = newS
return true
}
From What i read you are not passing the same "s" into your function as is in the rest of the code. I am sure there is a even better way but this is working for me.
You don't.
A var is a name that refers to a reference which might be changed. When you call a function, you pass the reference itself, and a new name gets bound to it.
So, to change what reference the name points to, you need a reference to whatever contains the name. If it is an object, that's easy enough. If it is a local variable, then it is not possible.
See also call by reference, though I don't think this question is a true duplicate.
If you just want to increment a variable starting with 3
val nextId = { var i = 3; () => { i += 1; i } }
then invoke it:
nextId()
s = s + 1so you are simply reassigning your local pointer to a new variable.