Re: RFC - Immutable classes

I agree. Will add this feature to RFC also Cheers On Sep 10, 2016 8:02 PM, "Marco Pivetta" <ocramius@gmail.com> wrote: > On Sat, Sep 10, 2016 at 7:49 PM, Niklas Keller <me@kelunik.com> wrote: > >> 2016-09-10 19:41 GMT+02:00 Silvio Marijić <marijic.silvio@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/ > >