Your "own" structs ... are they indeed passed by value?

I’d like to check something with a Unityscript expert … thanks!

Generally in Javascript - as I understand it - if something is a struct it is passed by value. (A new copy is made - if you change it you are doing nothing to the original). Whereas, if something is a class, it’s passed by reference. (No copy is made of the data. You are actually changing the values in the original.) [See footnote 1]

My question … as an everyday matter in UnityScript, you make “structs” or pseudo-structs, like this …

class EnormousThing extends System.ValueType
// huge amounts of stuff here

In fact, is it correct that such “pseudo-structs” are ALSO passed by value?

Another way to express this:

If you use “class EnormousThing” it will be passed by reference (“just as with all classes in Javascript”), whereas, if you use the “pseudo-struct” idiom: “class EnormousThing extends System.ValueType” it will be passed by value (|just as with real structs in Javascript")

is this exactly correct?

{As a further bonus question, in fact, is the only difference in adding “extends System.ValueType” in fact the value-versus-reference behaviour so described? Is that the only reason to add “extends System.ValueType” …? Is there really any other difference in using that qualifier?}

[Footnote 1] Although - this is a detail - cleverly the reference itself is I believe just a copy, so, if you set it to null you have done nothing to the original. Please completely ignore this issue in the question at hand.

It is correct that it will be passed by value. Another difference is that you will no longer be able to use a default constructor to initialize your values. You will get the default on all your members. (This link might help: