How to use Bitwise while setting properties

Sometimes we are faced with a situation, where a parameter can have multiple values, or even it can have combination of those values.

We have a few choices here, either we create multiple fields for each property, which is hard to scale but easier to understand.

Here is a code sample for that:

fun main() {
    order(true, true, false)
}

fun order(hasOrderedCheeseBurger: Boolean, hasOrderedFries: Boolean, hasOrderedSoda: Boolean) {
    println("Has Ordered CHEESEBURGER : ${hasOrderedCheeseBurger}"); // true
    println("Has Ordered FRIES : ${hasOrderedFries}"); // true
    println("Has Ordered SODA : ${hasOrderedSoda}"); // false
}

As you can see, we had to send 3 different parameters to know what this user had ordered and imagine, if, in future we need to add another item, let's say SANDWICH then we need to add another parameter.

---

Now, instead of passing multiple parameters, we can use bit manipulation to combine multiple parameters into a single parameter.

val CHEESEBURGER = 2; // 00000010
val FRIES = 4;        // 00000100
val SODA = 8;         // 00001000

fun main() {
    val ordered = CHEESEBURGER or FRIES;

    order(ordered)
}

fun order(what: Int) {
    val hasOrderedCheeseBurger = what and CHEESEBURGER == CHEESEBURGER;
    val hasOrderedFries = what and FRIES == FRIES;
    val hasOrderedSoda = what and SODA == SODA;
    println("Has Ordered CHEESEBURGER : ${hasOrderedCheeseBurger}"); // true
    println("Has Ordered FRIES : ${hasOrderedFries}"); // true
    println("Has Ordered SODA : ${hasOrderedSoda}"); // false
}

Here, bitwise allows us to add as many values as we need into a single parameter.