REPL question

Hi Christian,

do you use :paste mode?

scala> :paste
[then
write
multiple
lines
of
code]
<press ctrl-d>

scala>

If you are entering single lines, each line must compile “by itself” (i.e. can only reference stuff on previous lines).

Regards,

Roland

Am Sonntag, 1. Januar 2012 15:32:24 UTC+1 schrieb urbanc:

Hi,

I am often writing small scala programs using Emacs and the REPL.
However, whenever
I define something like

abstract class Rexp {
  def ~ (right : Rexp) = SEQ(this, right)
  def || (right : Rexp) = ALT(this, right)
  def ** = STAR(this)
}

case object NULL extends Rexp
case object EMPTY extends Rexp
case class CHAR(c: Char) extends Rexp
case class ALT(r1: Rexp, r2: Rexp) extends Rexp
case class SEQ(r1: Rexp, r2: Rexp) extends Rexp
case class STAR(r: Rexp) extends Rexp

then the REPL complains that the value for SEQ and ALT is not found in
the
abstract class. The compiler (scala) accepts such definitions. Is
there an elegant
way to make the REPL also accept such definitions? Of course I can
wrap
everything into an object and everything in a big chunk, but I hope
there is
a better solution.

Thanks for the help,
Christian

On Sun, Jan 01, 2012 at 06:32:24AM -0800, urbanc wrote:
> Hi,
>
> I am often writing small scala programs using Emacs and the REPL.
> However, whenever
> I define something like
>
> abstract class Rexp {
> def ~ (right : Rexp) = SEQ(this, right)
> def || (right : Rexp) = ALT(this, right)
> def ** = STAR(this)
> }
>
> case object NULL extends Rexp
> case object EMPTY extends Rexp
> case class CHAR(c: Char) extends Rexp
> case class ALT(r1: Rexp, r2: Rexp) extends Rexp
> case class SEQ(r1: Rexp, r2: Rexp) extends Rexp
> case class STAR(r: Rexp) extends Rexp
>
> then the REPL complains that the value for SEQ and ALT is not found in
> the
> abstract class. The compiler (scala) accepts such definitions. Is
> there an elegant
> way to make the REPL also accept such definitions? Of course I can
> wrap
> everything into an object and everything in a big chunk, but I hope
> there is
> a better solution.
>
> Thanks for the help,
> Christian
>

Does :paste answer your question?

Hi Shrivats,

Your suggestion definitely works (Thanks!). It would be
perfect, if Scala's emacs-mode had a magic key combination
to achieve the same (like C-c C-b or C-c C-r).

Best wishes and thanks again!
Christian

Shrivats writes:
> On Sun, Jan 01, 2012 at 06:32:24AM -0800, urbanc wrote:
> > Hi,
> >
> > I am often writing small scala programs using Emacs and the REPL.
> > However, whenever
> > I define something like
> >
> > abstract class Rexp {
> > def ~ (right : Rexp) = SEQ(this, right)
> > def || (right : Rexp) = ALT(this, right)
> > def ** = STAR(this)
> > }
> >
> > case object NULL extends Rexp
> > case object EMPTY extends Rexp
> > case class CHAR(c: Char) extends Rexp
> > case class ALT(r1: Rexp, r2: Rexp) extends Rexp
> > case class SEQ(r1: Rexp, r2: Rexp) extends Rexp
> > case class STAR(r: Rexp) extends Rexp
> >
> > then the REPL complains that the value for SEQ and ALT is not found in
> > the
> > abstract class. The compiler (scala) accepts such definitions. Is
> > there an elegant
> > way to make the REPL also accept such definitions? Of course I can
> > wrap
> > everything into an object and everything in a big chunk, but I hope
> > there is
> > a better solution.
> >
> > Thanks for the help,
> > Christian
> >
>
> Does :paste answer your question?
>

Hi,

I am trying to impose an alignment onto a
FlowPanel. Unfortunately, just writing

new FlowPanel(FlowPanel.Alignment.Left) { ... }

does not seem to work. In the snippet below
I get the error message

missing arguments for constructor FlowPanel in
class FlowPanel

While

new FlowPanel { ... }

works but centers all the content.

Thanks a lot!
Christian

import scala.swing._

object SampleGUI extends SimpleSwingApplication {
def top = new MainFrame {
title = "A Sample Scala Swing GUI"

val label = new Label { text = "------------"}
val button = new Button { text = "Click me" }

contents = new FlowPanel(FlowPanel.Alignment.Left) {
contents += label
contents += button
}
}
}

you have three constructors

• new FlowPanel ()
• new FlowPanel (contents0: Component*)
• new FlowPanel (alignment: Value)(contents0: Component*)

you try to use the last one, thus you need to specify the second argument list:

new FlowPanel(FlowPanel.Alignment.Left)(label, button)

best, -sciss-

On 7 Jan 2012, at 20:37, Christian Urban wrote:

>
> Hi,
>
> I am trying to impose an alignment onto a
> FlowPanel. Unfortunately, just writing
>
> new FlowPanel(FlowPanel.Alignment.Left) { ... }
>
> does not seem to work. In the snippet below
> I get the error message
>
> missing arguments for constructor FlowPanel in
> class FlowPanel
>
> While
>
> new FlowPanel { ... }
>
> works but centers all the content.
>
> Thanks a lot!
> Christian
>
>
> import scala.swing._
>
> object SampleGUI extends SimpleSwingApplication {
> def top = new MainFrame {
> title = "A Sample Scala Swing GUI"
>
> val label = new Label { text = "------------"}
> val button = new Button { text = "Click me" }
>
> contents = new FlowPanel(FlowPanel.Alignment.Left) {
> contents += label
> contents += button
> }
> }
> }