struct vs. class, int vs. char.

[Andrei Alexandrescu]

bearophile wrote:
> Yes, this is a problem of D2. Scala language shows that there are
> better ways to design types, as you say.

Could you please give a little more detail?

And speaking of Scala, after having watched a presentation, I was left 
with the impression that traits are nothing but classes with 
parameterized base.

I mean this:

abstract class Person {
   def schedule:Schedule
}

trait Student extends Person {
   private var classSchedule:Schedule = ...

   override def schedule = classSchedule

   def learn() = {...}
}

trait Worker extends Person {
   private var workSchedule:Schedule = ...

   override def schedule = workSchedule

   def work() = {...}
}

class CollegeStudent(school:School, company:Company) extends Student 
with Worker {
   // ...
}

is really this (in Scala-D made-up language):

abstract class Person {
   def schedule:Schedule
}

class Student(Base) extends Person {
   private var classSchedule:Schedule = ...

   override def schedule = classSchedule

   def learn() = {...}
}

class Worker(Base) extends Person {
   private var workSchedule:Schedule = ...

   override def schedule = workSchedule

   def work() = {...}
}

class CollegeStudent(school:School, company:Company) extends 
Worker!(Student!(CollegeStudent)) {
   // ...
}

Is that correct?


Andrei