partially applied classes

[Kubitz, Jörg]

Some parts of this message have been removed. Learn more about Nabble's security policy.

I am just reading about partially applied functions. So I wonder if there are partially applied classes too?

 

Scala compiles

 

class Complex(real: Double, imag: Double){

  //…

}

class Real(real: Double) extends Complex(real,0){}

 

But when I create an instance of Real my first guess is that the JVM would reserve Space for the private imag as well. Right or wrong? Does the Scala compiler replace the private member by a static final constant?

[Ricky Clarkson]

> So I wonder if there
> are partially applied classes too?

Nope.

> But when I create an instance of Real my first guess is that the JVM would
> reserve Space for the private imag as well. Right or wrong?

Right.

> Does the Scala
> compiler replace the private member by a static final constant?

Nope.  That would mean compiling two versions of all the code in
Complex, one using the constant and one using the private member.
That would break separate compilation.

--
Ricky Clarkson
Java and Scala Programmer, AD Holdings
[phone]
Skype: ricky_clarkson
Google Talk: ricky.clarkson@...
Google Wave: ricky.clarkson@...

[Ricky Clarkson]

Why would you need such a feature?

2009/11/6 Kubitz, Jörg <jkubitz@...>:

> Thanks for the fast reply.
>
> What a pitty. I would need such a feature.
>
> The following compiles:
>
>
>
> trait tComplex{
>
>   def real:Double
>
>   def imag:Double
>
>
>
> }
>
>
>
> trait tReal{
>
>   def value:Double
>
>
>
> }
>
>
>
> class Complex(r: Double, i: Double) extends tComplex{
>
>   def real:Double=r
>
>   def imag:Double=i
>
> }
>
>
>
> class Real(value: Double) extends tComplex {
>
>   def real:Double=value
>
>   def imag:Double=0
>
> }
>
>
>
> But that looks complicated. And I don’t know wheter “Traits” introduce
> runtime overhead which could result in poor Performance. Do they?
>
> Plus: This way a Real “is” not a Complex L
>
>
>
>
>
> -----Ursprüngliche Nachricht-----
> Von: Ricky Clarkson [mailto:ricky.clarkson@...]
> Gesendet: Freitag, 6. November 2009 12:43
> An: Kubitz, Jörg
> Cc: Scala Users
> Betreff: Re: [scala-user] partially applied classes
>
>
>
>> So I wonder if there
>
>> are partially applied classes too?
>
>
>
> Nope.
>
>
>
>> But when I create an instance of Real my first guess is that the JVM would
>
>> reserve Space for the private imag as well. Right or wrong?
>
>
>
> Right.
>
>
>
>> Does the Scala
>
>> compiler replace the private member by a static final constant?
>
>
>
> Nope.  That would mean compiling two versions of all the code in
>
> Complex, one using the constant and one using the private member.
>
> That would break separate compilation.
>
>
>
> --
>
> Ricky Clarkson
>
> Java and Scala Programmer, AD Holdings
>
> [phone]
>
> Skype: ricky_clarkson
>
> Google Talk: ricky.clarkson@...
>
> Google Wave: ricky.clarkson@...

--
Ricky Clarkson
Java and Scala Programmer, AD Holdings
[phone]
Skype: ricky_clarkson
Google Talk: ricky.clarkson@...
Google Wave: ricky.clarkson@...

[Ismael Juma]

On Fri, 2009-11-06 at 11:42 +0000, Ricky Clarkson wrote:
> > But when I create an instance of Real my first guess is that the JVM would
> > reserve Space for the private imag as well. Right or wrong?
>
> Right.

Actually there is not enough information in the example to say so. imag
could simply be a constructor parameter depending on what happens inside
the body of Complex.

Best,
Ismael