Specify Variable Initialization Order in Scala - scala

Question

I have a special class Model that needs to have its methods called in a very specific order.
I tried doing something like this:
val model = new Model
new MyWrappingClass {
val first = model.firstMethod()
val second = model.secondMethod()
val third = model.thirdMethod()
}
The methods should be called in the order listed, however I am seeing an apparently random order.
Is there any way to get the variable initialization methods to be called in a particular order?

Answer 1

I doubt your methods are called in the wrong order. But to be sure, you can try something like this:
val (first, second, third) = (
model.firstMethod(),
model.secondMethod(),
model.thirdMethod()
)
You likely have some other problem with your code.

Answer 2

I can run 100 million loops where it never gets the order wrong, as follows:
class Model {
var done = Array(false,false,false);
def firstMethod():Boolean = { done(0) = true; done(1) || done(2) };
def secondMethod():Boolean = { done(1) = true; !done(0) || done(2) };
def thirdMethod():Boolean = { done(2) = true; !done(0) || !done(1) };
};
Notice that these methods return a True if done out of order and false when called in order.
Here's your class:
class MyWrappingClass {
val model = new Model;
val first = model.firstMethod()
val second = model.secondMethod()
val third = model.thirdMethod()
};
Our function to check for bad behavior on each trial:
def isNaughty(w: MyWrappingClass):Boolean = { w.first || w.second || w.third };
A short program to test:
var i = 0
var b = false;
while( (i<100000000) && !b ){
b = isNaughty(new MyWrappingClass);
i += 1;
}
if (b){
println("out-of-order behavior occurred");
println(i);
} else {
println("looks good");
}
Scala 2.11.7 on OpenJDK8 / Ubuntu 15.04
Of course this doesn't prove it impossible to have wrong order, only that correct behavior seems highly repeatable in a fairly simple case.