----- Mail original -----
> De: "Brian Goetz" <[email protected]>
> À: "Remi Forax" <[email protected]>, "amber-spec-experts"
> <[email protected]>
> Envoyé: Samedi 24 Octobre 2020 23:47:42
> Objet: Re: Bad iteraction between the compact constructor and parameters
> captured by a lambda
> On 10/24/2020 4:45 PM, Remi Forax wrote:
>> 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
>> }
>> }
>
> But, is this any different than capturing any other constructor
> parameter that you mutate in the body?
Nope, but you don't have to re-assign the parameter is a plain old constructor,
you can use
this.parameter = parameter;
In a compact constructor, if you do a defensive copy, you have too change the
value of the parameter.
Rémi
