Bad iteraction between the compact constructor and parameters captured by a lambda

[Remi Forax]

Oops, instead of
  var copy = new int[items.length];
it should be
  var copy = new int[items.length][];

I've fixed the codes below.

----- Mail original -----
> De: "Remi Forax" <forax at univ-mlv.fr>
> À: "amber-spec-experts" <amber-spec-experts at openjdk.java.net>
> Envoyé: Samedi 24 Octobre 2020 22:45:15
> Objet: Bad iteraction between the compact constructor and parameters captured by a lambda

> When we have decided to ban
>  this.items = items
> in the compact constructor and ask our users to use an assignment instead,
> it has a stupid side effect to make the parameters inside the compact
> constructor not effectively final, so a lambda can not capture them.
> 
> So a code like this doesn't compile :(
>  
>  record Matrix(int[][] items) {
>    Matrix {
>      var copy = new int[items.length][];
>      Arrays.setAll(copy, i -> items[i].clone());
>      items = copy;  // items is not effectively final anymore
>    }
>  }
> 
> 
> 
> Obviouly, introducing an intermediary local variable works, but it's not pretty
> 
>  record Matrix(int[][] items) {
>    Matrix {
>      var copy = new int[items.length][];
>      var items2 = items;
>      Arrays.setAll(copy, i -> items2[i].clone());
>      items = copy;
>    }
>  }
> 
> 
> I'm not sure what we should do here :(
> I kind a like the current rules of a compact constructor.
> 
> Rémi