I think it would be very nice to be able to apply a trait directly to an object, without having to create a new class. This is possible for example in scala:
val myObject = new MyClass with MyTrait I have programmed a simple implementation in Pharo which allows you to do: myObject := (MyClass with: MyTrait) new. The implementation is only a proof of concept and has some issues that should be addressed before being able to use it in a real program, but I can make it available if someone is interested. What do you think about this? On Thu, Feb 16, 2012 at 11:04 AM, Hernan Wilkinson < hernan.wilkin...@10pines.com> wrote: > I have an idea about the state issue in traits, maybe you thought about it > too... I was thinking that the definition of representing something as > state or not should be responsibility of the implementation, that is the > class (nothing new here), so we delay that decision until the trait is > used. > So, maybe what we need is a way to indicate that a message send in a trait > is not really that in a class... For example: > > TraitA>>m1 > > ^self name first > > Object subclass: #ClassA > uses: #TraitA > mapping: (MessageSendToInstanceVariable from: #name to: 'firstName') > ... bla bla. > > So, #m1 in ClassA would look like: > > ClassA>>m1 > > ^firstName first > > Of course this implies some complexity when copying the behavior from the > trait to the class (we can not use the same compiled method), also > maintaining the relationship with changes on the trait (what happens if #m1 > is changed in TraitA and does not send #name anymore), etc. > First class slot (a la Self) would be a nicer solution, but I feel that > that implies a more radical change on the object model, vm, etc. and also > has the disadvantages of making all state public (unless something is done > to avoid that). > > At the same time, I would like to point out that having subclassing and > traits at the same time as sharing mechanism is kind of confusing, > programmers do not know which one is better to use, should I subclass or > use a trait? how I'm sure which one is better? etc. We talk about this when > you came to Argentina, do you remember? A student did his tesis about > removing subclassing and using only traits as sharing tool, but the results > were not as good as I expected (sadly, the thesis is written in Spanish...) > > Anyway, my two cents > Hernan. > > > On Thu, Feb 16, 2012 at 4:56 AM, Stéphane Ducasse < > stephane.duca...@inria.fr> wrote: > >> >> On Feb 15, 2012, at 11:30 PM, Hernan Wilkinson wrote: >> >> > what is the difference with the current trait implementation in pharo? >> I could not see the difference… >> >> Stefan replied but what I wanted to say is that I would like to have the >> time to see how we can introduce more nicely traits. >> Right now there are edges where this is ugly and also rethink the system. >> I think that if we would have first class slots we could have >> traits with state in a much better fashion. >> >> Stef >> >> > On Wed, Feb 15, 2012 at 7:45 AM, Stéphane Ducasse < >> stephane.duca...@inria.fr> wrote: >> > Indeed. Now I would love that we rethink our trait implementation and >> tool support but no time. >> > >> > On Feb 15, 2012, at 6:40 AM, blake wrote: >> > >> > > This is kinda cool: >> > > >> > > http://phpmaster.com/using-traits-in-php-5-4/ >> > > >> > >> > >> > >> > >> > >> > -- >> > Hernán Wilkinson >> > Agile Software Development, Teaching & Coaching >> > Mobile: +54 - 911 - 4470 - 7207 >> > email: hernan.wilkin...@10pines.com >> > site: http://www.10Pines.com >> > Address: Paraguay 523, Floor 7 N, Buenos Aires, Argentina >> > >> >> >> > > > -- > *Hernán Wilkinson > Agile Software Development, Teaching & Coaching > Mobile: +54 - 911 - 4470 - 7207 > email: hernan.wilkin...@10pines.com > site: http://www.10Pines.com <http://www.10pines.com/>* > Address: Paraguay 523, Floor 7 N, Buenos Aires, Argentina > >
