Re: [scala] Scala Object Notation ( SCON? )

Luckily, as the code is written its a copy of Roland, not Roland himself.

On 12/23/07, Viktor Klang <viktor.klang@...> wrote:
> On Dec 23, 2007 11:34 PM, Oscar Picasso <oscarpicasso@...> wrote:
>
> > We could also have?
> > rolandDumas.firstname("Bertrand").age(33)
>
>
> It feels instinctively wrong to have the Roland Dumas named Bertrand. :(
>
>
>
> >
> >
> > I am curious. Where in the lift code are you making these changes?
> >
> >
> > On Dec 23, 2007 5:05 PM, David Pollak < feeder.of.the.bears@...>
> > wrote:
> >
> > > I've been pestering the Scala folks for a way to update just one field
> > > in case classes and have a new instance spit out with just that one
> field
> > > changed for a very long time.
> > >
> > > It would work like this:
> > > val rolandDumas = Person("Roland", "Dumas", 0) // the factory instance
> > > val first= rolandDumas.age(43) // a new instance with age 43
> > > val second = rolandDumas.age(56) // yet another instance with age 56
> > >
> > > You'll be able to get that functionality with some of the changes I'm
> > > making to lift, but baking it into the language would be nicer.
> > >
> > >
> > > On Dec 23, 2007 9:10 AM, Oscar Picasso <oscarpicasso@...> wrote:
> > >
> > > > Case class was the first thing I thought when reading the beginning of
> > > > this tread.
> > > >
> > > > May it can be a partial answer to Rickard question.
> > > >
> > > > **case class Person(firstname: String, lastname: String, age: Int)
> > > >
> > > > But, in a small village in France, they are many Roland Dumas that
> > > > have different ages. Typing over and over Person("Roland", "Dumas",
> xxx) is
> > > > boring.
> > > >
> > > > So let's create a Roland Dumas maker.
> > > >
> > > > scala> def rolandDumasMaker = Person("Roland", "Dumas", _: Int)
> > > > rolandDumasMaker: (Int) => Person
> > > >
> > > > Now creating many Roland Dumases is becoming fun.
> > > > scala> rolandDumasMaker(45)
> > > > res5: Person = Person(Roland,Dumas,45)
> > > >
> > > > scala> rolandDumasMaker(85)
> > > > res6: Person = Person(Roland,Dumas,85)
> > > >
> > > > Sure, in many languages you can make this kind of factory but I find
> > > > it more meaningful and fun the way you can define it in scala.
> > > >
> > > >
> > > > On Dec 23, 2007 9:42 AM, David Pollak <feeder.of.the.bears@...m>
> > > > wrote:
> > > >
> > > > >
> > > > >
> > > > > On Dec 23, 2007 3:44 AM, David Bernard <david.bernard.31@...m>
> > > > > wrote:
> > > > >
> > > > > > I thinks that with some change in Property you could support a
> > > > > > builder approach that support
> > > > > > val w = new Widget()
> > > > > >        .name("MyWidget")
> > > > > >        .height(10)
> > > > > >        .children(label, panel, button)
> > > > >
> > > > >
> > > > > Which is what you get with lift components.
> > > > >
> > > > > But I believe the larger issue is one of mutability and internal
> > > > > type representation.
> > > > >
> > > > > JavaScript has JSON because it is pretty much built on hash tables
> > > > > and the built in types (numbers, Strings, dates, booleans, arrays
> and
> > > > > hashs/objects) are so limited in number that it makes sense to have
> special
> > > > > syntax for each of them.
> > > > >
> > > > > Scala, too, has some special notation for building object
> > > > > hierarchies: case classes.  One can build complex object hierarchies
> using
> > > > > case classes.  In my opinion, they are as easy to read as JSON
> objects.
> > > > > They are a little more verbose to type, but that's because they're
> typed (ah
> > > > > hah... a pun.)
> > > > >
> > > > > One can also do:
> > > > > Map('foo -> Array(1,2,3), 'bar -> Array("dog", "cat"), 'baz ->
> > > > > Date("12-23-07"))
> > > > >
> > > > > It's a little more verbose than JSON, but the objects are
> > > > > serializable as JSON (okay, I made up the Date thing, but it's not
> hard to
> > > > > implement.)
> > > > >
> > > > > If you want the kind of unstructured hash tables you get with
> > > > > JavaScript, use Maps/Arrays (or Lists).  If you want more structured
> stuff,
> > > > > where are case classes lacking?
> > > > >
> > > > > Thanks,
> > > > >
> > > > > David
> > > > >
> > > > >
> > > > > >
> > > > > >
> > > > > > my 2 cents.
> > > > > >
> > > > > > /davidB
> > > > > >
> > > > > > Andrés Testi wrote:
> > > > > > > Yes, but I don't like the fact of create a subclass of Person. I
> > > > > > just
> > > > > > > want to instantiate a Person. Suppose you have this Widget
> > > > > > class:
> > > > > > >
> > > > > > > class Widget{
> > > > > > >   val name  = new Property("")
> > > > > > >   val width = new Property(0)
> > > > > > >   val height = new Property(0)
> > > > > > >   val children  = new Property(Array[Widget]())
> > > > > > > }
> > > > > > >
> > > > > > > To populate the Widget properties without Object notation, you
> > > > > > need to
> > > > > > > write the next code
> > > > > > >
> > > > > > > val w = new Widget
> > > > > > > p.name() = "MyWidget"
> > > > > > > p.height() = 10
> > > > > > > p.children() = Array(
> > > > > > >   label, panel,button
> > > > > > > )
> > > > > > >
> > > > > > > the previous code is not Property-Editor friendly, because the
> > > > > > > "programmatic" nature. Then, a declarative syntax is the key.
> > > > > > But
> > > > > > > creating annonimous class is not declarative but programmatic,
> > > > > > because
> > > > > > > I would to assign a property 2 times:
> > > > > > >
> > > > > > > new Widget{
> > > > > > >   name="MyWidget"
> > > > > > >   name="YourWidget"
> > > > > > > }
> > > > > > >
> > > > > > > In the other hand, I don't like to subclass Widget, because I
> > > > > > just
> > > > > > > want to instantiate Widget.
> > > > > > >
> > > > > > > 2007/12/22, martin odersky < martin.odersky@...>:
> > > > > > >>> Hello:
> > > > > > >>> Is it possible to instantiate scala objects in a declarative
> > > > > > way like
> > > > > > >>> JSON. I think this would be a solution:
> > > > > > >>>
> > > > > > >>> val p = new Person{
> > > > > > >>>    name = "Peter"
> > > > > > >>>    age = 20
> > > > > > >>>    friends = Array(
> > > > > > >>>       new Person{
> > > > > > >>>           name = "Gary"
> > > > > > >>>       }
> > > > > > >>>    )
> > > > > > >>>
> > > > > > >>> }
> > > > > > >>>
> > > > > > >> Sure. That you wrote is legal Scala, assuming you declared
> > > > > > Person like this:
> > > > > > >>
> > > > > > >>   class Person {
> > > > > > >>      var name: String = ""
> > > > > > >>      var age: Int = 99
> > > > > > >>      var friends: Array[Person] = Array()
> > > > > > >>   }
> > > > > > >>
> > > > > > >> But maybe that's not what you wanted?
> > > > > > >>
> > > > > > >> Cheers
> > > > > > >>
> > > > > > >>  -- Martin
> > > > > > >>
> > > > > >
> > > > > >
> > > > >
> > > > >
> > > > > --
> > > > > lift, the secure, simple, powerful web framework http://liftweb.net
> > > > > Collaborative Task Management http://much4.us
> > > >
> > > >
> > > >
> > >
> > >
> > > --
> > > lift, the secure, simple, powerful web framework http://liftweb.net
> > > Collaborative Task Management http://much4.us
> > >
> >
> >
>
>
> --
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