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kotlinlang

what's the difference of defining:
class MyClass(val a:String, val b:String)
from
class MyClass(a:String, b:String)

If you use `class Foo(a: String, b: String)` you say that you want the primary constructor to take 2 arguments (a and b). If you add `val` or `var` you also create 2 properties in the class which will automatically get assigned the arguments passed to the constructor.

So `class Foo(val a: String)` is a short for
```
class Foo (a: String) {
    val a: String = a
}
```

great that's what I thought as well trying to test it eheheh

and that's why data classes can only be with val, makes sense

they can also use `var` but they should all be properties certainly

<https://kotlinlang.org/docs/reference/classes.html>