On Sat, Sep 10, 2016 at 7:49 PM, Niklas Keller <m...@kelunik.com> wrote:
> 2016-09-10 19:41 GMT+02:00 Silvio Marijić <marijic.sil...@gmail.com>:
>
> > @Fleshgrinder,
> >
> > While I'm not sure at the moment about CoW, I can agree that we should
> add
> > immutable keyword as a interface modifier to make sure all classes
> > implementing must be immutable.
>
>
> As interfaces can't have member variables, that doesn't make sense to me.
>
It still makes sense from a consumer perspective, so having the restriction
in the contract is quite good.
If you accept a `Number`, you expect to be able to serialize/de-serialize
it, and you expect it to be "locked", immutable.
If you let an implementation of `Number` to have mutable state in, then you
break all the code that relies on `Number`.
Note that it is still possible to break this though, so maybe we'd need
some other modifiers about behavior too (pure function modifier?)
immutable interface Number
{
public function toFloat() : float;
}
immutable class RandomNumber implements Number
{
public function toFloat() : float { return (float) random_int(1,
100000); /* yo, look at my global mutable hidden state! */ }
}
Requiring immutable values in consumers will likely improve code
quality/safety and reduce dangerous assumptions, and it will probably also
allow for optimizations in the engine later on.
Marco Pivetta
http://twitter.com/Ocramius
http://ocramius.github.com/
