When creating a variable using val or var and assigning the value of an expression into it the expression is evaluated when the variable is created. When creating a function using def and assigning the value of an expression to it the expression is evaluated when calling the function.
object Program {
def main(args: Array[String]):Unit =
{
var a = 3
var b = 4
var c = 5
val e1 = if (b>a) "spiderman" else "wonderwoman"
var e2 = if (b>a) "spiderman" else "wonderwoman"
def e3 = if (b>a) "spiderman" else "wonderwoman"
a = 7
println(e1)
println(e2)
println(e3)
}
}
The following video clip goes over this code sample and explains it.
