Using Setters within a Scala method - scala

Question

Introduction
Aim: to use (multiple) setters in a Scala method.
Test
test("testCity") {
val numberSequences = new NumberSequences()
numberSequences.test("utrecht")
assert("utrecht" === numberSequences.city)
}
Code
var _city: String = null
def city_=(_city:String) = this._city = _city
def city = this._city
def test(s: String) : String = {
city_=(s)
}
Output
The error indicates that there is a type match, which is strange as numberSequences.city_=("utrecht") in the test works.
> test
[info] Compiling 1 Scala source to C:\path\to\developme
nt\scalaNumberSequences\target\scala-2.10\classes...
[error] C:\path\to\development\scalaNumberSequences\src
\main\scala\com\utrecht\numbersequences\NumberSequences.scala:86: type mismatch;
[error] found : Unit
[error] required: String
[error] city_=(s)
[error] ^
[error] one error found
[error] (compile:compile) Compilation failed
[error] Total time: 1 s, completed Aug 10, 2014 8:53:37 PM

Answer 1

def test(s: String) : String = {
city_=(s)
}
Here you set the variable of the var city_, but your method signature says it should return a String, the return type of a function comes from the last line and assignment has no return type, either return some string at the end:
def test(s: String): String = {
city_=(s)
s
}
Or make it a setter-like method and return unit:
def test(s: String): Unit = {
city_=(s)
}