+=/*=/etc operators on AnyVal types (Int,Double,etc...) in Scala

Question

Where exactly are the *=/+=/etc methods declared for the subclasses of AnyVal? I assume something special is done for these types because as a val those are invalid but as a var they are fine. Is this just yet more syntatic sugar ? I assume it is turning

a *= 5

into

a = a * 5

which obviously fails for a val. Is this intuition correct? I also assume it only attempts this for AnyVals?

Thanks :)

Answer 1

Your intuition is correct. For any class, not only the subclasses of AnyVal, if an assignment method does not exists, then a OP= b is turned into a = a OP b. Mind you, OP, in this case, must be non-alphanumeric characters.