I am trying to do what is mentioned below but am struggling with the
object side of things for my particular case. This all relates back
to trying to auto-generate some classes that I posted back a while ago
on. I would love to generate 1 file that has the trait and the object
in it that I then inherit from in my sub-class and object sub-class in
another file.
Autogenerated.scala
trait FC[MapperType <: FC[MapperType]] extends Mapper[MapperType] {
self: MapperType =>
object today extends MappedLong(this)
}
trait FCObj extends FC[MapperType] with LongKeyedMetaMapper[FC
[MapperType]] {
override def fieldOrder = List(today)
}
In UserClass.scala
class FC_Wrapper extends LongKeyedMapper[FC_Wrapper] with IdPK with FC
[Wrapper] {
def getSingleton = FCObj_Wrapper
// define methods
}
object FCObj_Wrapper extends FCObj {
// define auxiliary functionality
}
I know that the FCObj and FCObj_Wrapper is not correct syntax wise.
But the basic idea is that I want to have my autogeneration generate
the boilerplate code for me in a separate file. This boilerplate
would ideally include the class and object related stuff. Then in a
file that won't be stomped upon the next time I run the generator I
inherit from these objects. I hope this makes sense.
I admit to not totally understanding the templated/generic programming
that is happening.
On Sep 3, 1:33 pm, glenn <gl...@exmbly.com> wrote:
> Isn't this really a matter of type casting, and asInstanceOf is just
> Scala's
> way of doing this. It's always best if you don't have to downcast your
> objects, but sometimes its unavoidable.
>
> Glenn...
>
> On Sep 3, 10:29 am, glenn <gl...@exmbly.com> wrote:
>
> > I'm not sure of what the exact problem is. I created an Address trait
> > that
> > I couple with a number of mapper classes.
>
> > trait Address[OwnerType <: KeyedMapper[Long, OwnerType]]{
>
> > def owner = this.asInstanceOf[OwnerType]
>
> > ....
>
> > Where exactly does this construct break down?
>
> > Glenn...
>
> > On Sep 3, 7:55 am, Giuseppe Fogliazza <g.foglia...@mcmspa.it> wrote:
>
> > > jon suggested to me the way to avoid both explicit type parameter and
> > > asinstance of:
> > > trait Timestamp[MapperType <: TimeStamp[MapperType]] extends Mapper
> > > [MapperType] {
> > >self:MapperType =>
> > > object xdatetime extends MappedDateTime(this)
>
> > > // all sorts of utility functions for dealing with timestamps
>
> > > }
>
> > > Thanks jon I have improved model in my application with this approach.
>
> > > Giuseppe
>
> > > On 3 Set, 16:16, Giuseppe Fogliazza <g.foglia...@mcmspa.it> wrote:
>
> > > > As an alternative to asInstanceOf you could use explicit type
> > > > parameter in MappedField creation:
> > > >self:MapperType =>
> > > > object xdatetime extends MappedDateTime[MapperType](this)
>
> > > > On 3 Set, 09:19, Giuseppe Fogliazza <g.foglia...@mcmspa.it> wrote:
>
> > > > > Unfortunately you cannot escape from asInstanceOf . Forcing
> > > > >self:MapperType the type of "this" will be TimeStamp with MapperType
> > > > > violating the constraint for the type of the first parameter of
> > > > > MappedDateTime :T <: Mapper[T].
>
> > > > > Regards
> > > > > Giuseppe
>
> > > > > On 3 Set, 07:08, Naftoli Gugenheim <naftoli...@gmail.com> wrote:
>
> > > > > > So I guess you can't escape the asInstanceOf. Can you successfully
> > > > > > give the trait aself-type of this: MapperType =>, or declare it to
> > > > > > extend Mapper[MapperType], without running into problems elsewhere?
>
> > > > > > -------------------------------------
>
> > > > > > harryh<har...@gmail.com> wrote:
>
> > > > > > I've been handling this with traits, for example I have something
> > > > > > like
> > > > > > so:
>
> > > > > > trait Timestamp[MapperType <: Mapper[MapperType]] {
> > > > > > object xdatetime extends
> > > > > > MappedDateTime[MapperType](this.asInstanceOf
> > > > > > [MapperType])
>
> > > > > > // all sorts of utility functions for dealing with timestamps
>
> > > > > > }
>
> > > > > > Then I can do
>
> > > > > > class Foo extends LongKeyedMapper[Foo] with IdPK with
> > > > > > Timestamp[Foo] {
> > > > > > // additional fields that are Foo specific
>
> > > > > > }
>
> > > > > > I have quite a few traits similar to Timestamp at this point
> > > > > > corresponding to various fields that appear in lots of different
> > > > > > tables in my application.
>
> > > > > > -harryh
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