Scala Forum

Re: Extention of Enumeration

2010-09-05T22:30:19+02:00

When it comes to something like page size or display resolution (in definite contrast to page orientation), I question whether a statically enumerated set of values is appropriate. One (orientation) clearly has a universe of values that is fixed forever—either a page is in portrait orientation or it's in landscape orientation (or the paper is square...). On the other hand, page sizes and rendering resolutions definitely do not comprise an intrinsically finite collection of values.

I'd consider representing the page sizes and display resolutions with types whose values are initialized dynamically and configurably.

Randall Schulz

Re: StackOverflow beim compilieren?

2010-09-05T21:50:59+02:00

Ich habe jetzt die Stelle gefunden. Es handelt sich um

Language: Scala
object Obj {
  val arr = Array[(Double, Double, Double, Double, Double)] (
  // wird mit 64 x 64 Elementen gefüllt
  // --> arr.size = 64 x 64 / 5
  )
}

Wie bekomme ich das nun compiliert?

Re: Scala Swing Grafiken einfügen

2010-09-05T21:48:07+02:00

javax.swing.Icon

Language: Scala
import swing._
val label = new Label { icon = new ImageIcon(getClass.getResource("...") }

Re: Extention of Enumeration

2010-09-05T20:01:14+02:00

Meanwhile I found a solution in the internet.
[downgra.de]

Following the example from 'fire' my solution for three enums (Orientation, Resolution and PageSize) is the following.

Language: Scala
object Orientation extends Enumeration {
    type Orientation = Value
 
    val LANDSCAPE, PORTRAIT = Value
  }
 
  object Resolution extends Enumeration {
    case class ResolutionVal(val name: String, val dpi: Int) extends Val(name)
    type Resolution = ResolutionVal
 
    val DPI70 = ResolutionVal("DPI-70", 70)
    val DPI300 = ResolutionVal("DPI-300", 300)
  }
 
  import Orientation._
  import Resolution._
 
  object PageSize extends Enumeration {
 
    case class PageSizeValue(val name: String, val width70: Int, val height70: Int) {
 
      // Returns the width in pixel according to resolution and orientation
      def width(resolution: Resolution, orientation: Orientation): Int = {
        orientation match {
          case LANDSCAPE => (height70.toDouble / 70.0 * resolution.dpi).toInt
          case PORTRAIT => (width70.toDouble / 70.0 * resolution.dpi).toInt
          case _ => throw new IllegalArgumentException("Unknown 'Orientation' " + orientation)
        }
      }
      // Returns the height in pixel according to resolution and orientation
      def height(resolution: Resolution, orientation: Orientation): Int = {
        orientation match {
          case LANDSCAPE => (width70.toDouble / 70.0 * resolution.dpi).toInt
          case PORTRAIT => (height70.toDouble / 70.0 * resolution.dpi).toInt
          case _ => throw new IllegalArgumentException("Unknown 'Orientation' " + orientation)
        }
      }
    }
 
    type PageSize = PageSizeValue
 
    val A0 = PageSizeValue("A0", 2318, 3277)
    val A1 = PageSizeValue("A1", 1637, 2318)
    val A2 = PageSizeValue("A2", 1157, 1637)
    val A3 = PageSizeValue("A3", 819, 1157)
    val A4 = PageSizeValue("A4", 579, 819)
    val A5 = PageSizeValue("A5", 408, 579)
    val A6 = PageSizeValue("A6", 289, 408)
  }
 
  import PageSize._
 
Critique welcome !!

Re: Extention of Enumeration

2010-09-05T18:47:20+02:00

Instead of this:

Language: Scala
class R(_name: String, _dpi: Int) extends Enumeration
{
    val name = _name
    val dpi = _dpi
}

Write this:

Language: Scala
class R(val name: String, val dpi: Int) extends Enumeration

They are the same.

Randall Schulz

Re: Extention of Enumeration

2010-09-05T18:09:30+02:00

Thanks for this Answer. That worked fine. What I actually wanted is an Enumeration with two attributes like the following:

Language: Scala
class R (_name: String, _dpi: Int) extends Enumeration {
 
    val name = _name
    val dpi = _dpi
 
  }
 
  object Resolution extends R {
	  ????? = value
  }

Is there a solution to have somthing like the following.

rough("R", 70), fine("F", 300)

??

Re: StackOverflow beim compilieren?

2010-09-05T18:00:43+02:00

Wie kann ich rausfinden, an welcher Datei es liegt?

Re: StackOverflow beim compilieren?

2010-09-05T17:28:16+02:00

Ok. Ich bin nun auf folgendes gestossen
[www.scala-lang.org]

wie es aussieht, ist es ein generelles Problem. Eine Erhöhung des Stack's brachte keine abhilfe :-(

Re: Scala Swing Grafiken einfügen

2010-09-05T17:19:08+02:00

Ja ich möchte eine Grafik anzeigen, einfach eine Bitmap in einem Label anzeigen oder ähnliches.

javax.swing.ImageIcon wird nicht funktionieren. Ich benutze MigLayout und er verlangt Scala-Components.

Die Klasse Icon finde ich nicht im Scala-doc. In welchem Paket ist die?

StackOverflow beim compilieren?

2010-09-05T16:06:20+02:00

Servus,

beim compilieren mit Maven bekomme ich eine StackOverflow-Exception. Leider kann ich den Ort nicht zu 100% ausmachen, aber ich denke mal das es an dem folgenden Codestück liegt.

Wie kann ich den Überlauf verhindern?
Die Arrays enthalten jetzt nicht so viel Elemente. Wieso wird hier bereits ein Überlauf produziert?

Compiling 133 source files to... at 1283695019242
java.lang.reflect.InvocationTargetException
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org_scala_tools_maven_executions.MainHelper.runMain(MainHelper.java:151)
        at org_scala_tools_maven_executions.MainWithArgsInFile.main(MainWithArgsInFile.java:26)
[ERROR]Caused by: java.lang.StackOverflowError
        at scala.tools.nsc.typechecker.Typers$Typer.gd9$1(Typers.scala:785)
        at scala.tools.nsc.typechecker.Typers$Typer.adapt(Typers.scala:771)
        at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:4083)
        at scala.tools.nsc.typechecker.Typers$Typer.typedTypeConstructor(Typers.scala:4189)
        at scala.tools.nsc.typechecker.Typers$Typer.typedTypeConstructor(Typers.scala:4212)
        at scala.tools.nsc.typechecker.Typers$Typer.typedNew$1(Typers.scala:3140)
        at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:3849)
        at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:4078)
        at scala.tools.nsc.typechecker.Typers$Typer.typedQualifier(Typers.scala:4145)
        at scala.tools.nsc.typechecker.Typers$Typer.typedQualifier(Typers.scala:4151)
        at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:3964)
        at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:4078)
        at scala.tools.nsc.typechecker.Typers$Typer.typedOperator(Typers.scala:4157)
        at scala.tools.nsc.typechecker.RefChecks$RefCheckTransformer.toConstructor(RefChecks.scala:797)
        at scala.tools.nsc.typechecker.RefChecks$RefCheckTransformer.transformCaseApply(RefChecks.scala:1008)
        at scala.tools.nsc.typechecker.RefChecks$RefCheckTransformer.transform(RefChecks.scala:1146)
        at scala.tools.nsc.ast.Trees$Transformer.transform(Trees.scala:804)
        at scala.tools.nsc.typechecker.RefChecks$RefCheckTransformer.transform(RefChecks.scala:1183)
        at scala.tools.nsc.ast.Trees$Transformer$$anonfun$transformTrees$1.apply(Trees.scala:838)
        at scala.tools.nsc.ast.Trees$Transformer$$anonfun$transformTrees$1.apply(Trees.scala:838)
        at scala.collection.immutable.List.loop$1(List.scala:115)
        at scala.collection.immutable.List.mapConserve(List.scala:132)
        at scala.collection.immutable.List.loop$1(List.scala:119)
        at scala.collection.immutable.List.mapConserve(List.scala:132)
        at scala.collection.immutable.List.loop$1(List.scala:119)
        at scala.collection.immutable.List.mapConserve(List.scala:132)
        at scala.collection.immutable.List.loop$1(List.scala:119)
        at scala.collection.immutable.List.mapConserve(List.scala:132)
        at scala.collection.immutable.List.loop$1(List.scala:119)
        at scala.collection.immutable.List.mapConserve(List.scala:132)
        at scala.collection.immutable.List.loop$1(List.scala:119)
        at scala.collection.immutable.List.mapConserve(List.scala:132)
        at scala.collection.immutable.List.loop$1(List.scala:119)
        at scala.collection.immutable.List.mapConserve(List.scala:132)
        at scala.collection.immutable.List.loop$1(List.scala:119)
        at scala.collection.immutable.List.mapConserve(List.scala:132)
        at scala.collection.immutable.List.loop$1(List.scala:119)
        at scala.collection.immutable.List.mapConserve(List.scala:132)
        at scala.collection.immutable.List.loop$1(List.scala:119)
        at scala.collection.immutable.List.mapConserve(List.scala:132)
        at scala.collection.immutable.List.loop$1(List.scala:119)
....

Im Orginal sind mehrere Zeilen dieser Form (Array von (Double, Double) oder (Double, Double, Double, Double)) und Länge enthalten.

Language: Scala
object CIE {
  // ....
 
  /**
   * Standard illuminants: CIE Illuminant D65
   *
   */
  private[this] lazy val Illuminantd65 = Array[(Double, Double)] (
    (300, 0.034100),
    (301, 0.360140),
    (302, 0.686180),
    (303, 1.012220),
    (304, 1.338260),
    (305, 1.664300),
    (306, 1.990340),
    (307, 2.316380),
    (308, 2.642420),
    (309, 2.968460),
    (310, 3.294500),
    (311, 4.988650),
    (312, 6.682800),
    (313, 8.376950),
    (314, 10.071100),
    (315, 11.765200),
    (316, 13.459400),
    (317, 15.153500),
    (318, 16.847700),
    (319, 18.541800),
    (320, 20.236000),
    (321, 21.917700),
    (322, 23.599500),
    (323, 25.281200),
    (324, 26.963000),
    (325, 28.644700),
    (326, 30.326500),
    (327, 32.008200),
    (328, 33.690000),
    (329, 35.371700),
    (330, 37.053500),
    (331, 37.343000),
    (332, 37.632600),
    (333, 37.922100),
    (334, 38.211600),
    (335, 38.501100),
    (336, 38.790700),
    (337, 39.080200),
    (338, 39.369700),
    (339, 39.659300),
    (340, 39.948800),
    (341, 40.445100),
    (342, 40.941400),
    (343, 41.437700),
    (344, 41.934000),
    (345, 42.430200),
    (346, 42.926500),
    (347, 43.422800),
    (348, 43.919100),
    (349, 44.415400),
    (350, 44.911700),
    (351, 45.084400),
    (352, 45.257000),
    (353, 45.429700),
    (354, 45.602300),
    (355, 45.775000),
    (356, 45.947700),
    (357, 46.120300),
    (358, 46.293000),
    (359, 46.465600),
    (360, 46.638300),
    (361, 47.183400),
    (362, 47.728500),
    (363, 48.273500),
    (364, 48.818600),
    (365, 49.363700),
    (366, 49.908800),
    (367, 50.453900),
    (368, 50.998900),
    (369, 51.544000),
    (370, 52.089100),
    (371, 51.877700),
    (372, 51.666400),
    (373, 51.455000),
    (374, 51.243700),
    (375, 51.032300),
    (376, 50.820900),
    (377, 50.609600),
    (378, 50.398200),
    (379, 50.186900),
    (380, 49.975500),
    (381, 50.442800),
    (382, 50.910000),
    (383, 51.377300),
    (384, 51.844600),
    (385, 52.311800),
    (386, 52.779100),
    (387, 53.246400),
    (388, 53.713700),
    (389, 54.180900),
    (390, 54.648200),
    (391, 57.458900),
    (392, 60.269500),
    (393, 63.080200),
    (394, 65.890900),
    (395, 68.701500),
    (396, 71.512200),
    (397, 74.322900),
    (398, 77.133600),
    (399, 79.944200),
    (400, 82.754900),
    (401, 83.628000),
    (402, 84.501100),
    (403, 85.374200),
    (404, 86.247300),
    (405, 87.120400),
    (406, 87.993600),
    (407, 88.866700),
    (408, 89.739800),
    (409, 90.612900),
    (410, 91.486000),
    (411, 91.680600),
    (412, 91.875200),
    (413, 92.069700),
    (414, 92.264300),
    (415, 92.458900),
    (416, 92.653500),
    (417, 92.848100),
    (418, 93.042600),
    (419, 93.237200),
    (420, 93.431800),
    (421, 92.756800),
    (422, 92.081900),
    (423, 91.406900),
    (424, 90.732000),
    (425, 90.057000),
    (426, 89.382100),
    (427, 88.707100),
    (428, 88.032200),
    (429, 87.357200),
    (430, 86.682300),
    (431, 88.500600),
    (432, 90.318800),
    (433, 92.137100),
    (434, 93.955400),
    (435, 95.773600),
    (436, 97.591900),
    (437, 99.410200),
    (438, 101.228000),
    (439, 103.047000),
    (440, 104.865000),
    (441, 106.079000),
    (442, 107.294000),
    (443, 108.508000),
    (444, 109.722000),
    (445, 110.936000),
    (446, 112.151000),
    (447, 113.365000),
    (448, 114.579000),
    (449, 115.794000),
    (450, 117.008000),
    (451, 117.088000),
    (452, 117.169000),
    (453, 117.249000),
    (454, 117.330000),
    (455, 117.410000),
    (456, 117.490000),
    (457, 117.571000),
    (458, 117.651000),
    (459, 117.732000),
    (460, 117.812000),
    (461, 117.517000),
    (462, 117.222000),
    (463, 116.927000),
    (464, 116.632000),
    (465, 116.336000),
    (466, 116.041000),
    (467, 115.746000),
    (468, 115.451000),
    (469, 115.156000),
    (470, 114.861000),
    (471, 114.967000),
    (472, 115.073000),
    (473, 115.180000),
    (474, 115.286000),
    (475, 115.392000),
    (476, 115.498000),
    (477, 115.604000),
    (478, 115.711000),
    (479, 115.817000),
    (480, 115.923000),
    (481, 115.212000),
    (482, 114.501000),
    (483, 113.789000),
    (484, 113.078000),
    (485, 112.367000),
    (486, 111.656000),
    (487, 110.945000),
    (488, 110.233000),
    (489, 109.522000),
    (490, 108.811000),
    (491, 108.865000),
    (492, 108.920000),
    (493, 108.974000),
    (494, 109.028000),
    (495, 109.082000),
    (496, 109.137000),
    (497, 109.191000),
    (498, 109.245000),
    (499, 109.300000),
    (500, 109.354000),
    (501, 109.199000),
    (502, 109.044000),
    (503, 108.888000),
    (504, 108.733000),
    (505, 108.578000),
    (506, 108.423000),
    (507, 108.268000),
    (508, 108.112000),
    (509, 107.957000),
    (510, 107.802000),
    (511, 107.501000),
    (512, 107.200000),
    (513, 106.898000),
    (514, 106.597000),
    (515, 106.296000),
    (516, 105.995000),
    (517, 105.694000),
    (518, 105.392000),
    (519, 105.091000),
    (520, 104.790000),
    (521, 105.080000),
    (522, 105.370000),
    (523, 105.660000),
    (524, 105.950000),
    (525, 106.239000),
    (526, 106.529000),
    (527, 106.819000),
    (528, 107.109000),
    (529, 107.399000),
    (530, 107.689000),
    (531, 107.361000),
    (532, 107.032000),
    (533, 106.704000),
    (534, 106.375000),
    (535, 106.047000),
    (536, 105.719000),
    (537, 105.390000),
    (538, 105.062000),
    (539, 104.733000),
    (540, 104.405000),
    (541, 104.369000),
    (542, 104.333000),
    (543, 104.297000),
    (544, 104.261000),
    (545, 104.225000),
    (546, 104.190000),
    (547, 104.154000),
    (548, 104.118000),
    (549, 104.082000),
    (550, 104.046000),
    (551, 103.641000),
    (552, 103.237000),
    (553, 102.832000),
    (554, 102.428000),
    (555, 102.023000),
    (556, 101.618000),
    (557, 101.214000),
    (558, 100.809000),
    (559, 100.405000),
    (560, 100.000000),
    (561, 99.633400),
    (562, 99.266800),
    (563, 98.900300),
    (564, 98.533700),
    (565, 98.167100),
    (566, 97.800500),
    (567, 97.433900),
    (568, 97.067400),
    (569, 96.700800),
    (570, 96.334200),
    (571, 96.279600),
    (572, 96.225000),
    (573, 96.170300),
    (574, 96.115700),
    (575, 96.061100),
    (576, 96.006500),
    (577, 95.951900),
    (578, 95.897200),
    (579, 95.842600),
    (580, 95.788000),
    (581, 95.077800),
    (582, 94.367500),
    (583, 93.657300),
    (584, 92.947000),
    (585, 92.236800),
    (586, 91.526600),
    (587, 90.816300),
    (588, 90.106100),
    (589, 89.395800),
    (590, 88.685600),
    (591, 88.817700),
    (592, 88.949700),
    (593, 89.081800),
    (594, 89.213800),
    (595, 89.345900),
    (596, 89.478000),
    (597, 89.610000),
    (598, 89.742100),
    (599, 89.874100),
    (600, 90.006200),
    (601, 89.965500),
    (602, 89.924800),
    (603, 89.884100),
    (604, 89.843400),
    (605, 89.802600),
    (606, 89.761900),
    (607, 89.721200),
    (608, 89.680500),
    (609, 89.639800),
    (610, 89.599100),
    (611, 89.409100),
    (612, 89.219000),
    (613, 89.029000),
    (614, 88.838900),
    (615, 88.648900),
    (616, 88.458900),
    (617, 88.268800),
    (618, 88.078800),
    (619, 87.888700),
    (620, 87.698700),
    (621, 87.257700),
    (622, 86.816700),
    (623, 86.375700),
    (624, 85.934700),
    (625, 85.493600),
    (626, 85.052600),
    (627, 84.611600),
    (628, 84.170600),
    (629, 83.729600),
    (630, 83.288600),
    (631, 83.329700),
    (632, 83.370700),
    (633, 83.411800),
    (634, 83.452800),
    (635, 83.493900),
    (636, 83.535000),
    (637, 83.576000),
    (638, 83.617100),
    (639, 83.658100),
    (640, 83.699200),
    (641, 83.332000),
    (642, 82.964700),
    (643, 82.597500),
    (644, 82.230200),
    (645, 81.863000),
    (646, 81.495800),
    (647, 81.128500),
    (648, 80.761300),
    (649, 80.394000),
    (650, 80.026800),
    (651, 80.045600),
    (652, 80.064400),
    (653, 80.083100),
    (654, 80.101900),
    (655, 80.120700),
    (656, 80.139500),
    (657, 80.158300),
    (658, 80.177000),
    (659, 80.195800),
    (660, 80.214600),
    (661, 80.420900),
    (662, 80.627200),
    (663, 80.833600),
    (664, 81.039900),
    (665, 81.246200),
    (666, 81.452500),
    (667, 81.658800),
    (668, 81.865200),
    (669, 82.071500),
    (670, 82.277800),
    (671, 81.878400),
    (672, 81.479100),
    (673, 81.079700),
    (674, 80.680400),
    (675, 80.281000),
    (676, 79.881600),
    (677, 79.482300),
    (678, 79.082900),
    (679, 78.683600),
    (680, 78.284200),
    (681, 77.427900),
    (682, 76.571600),
    (683, 75.715300),
    (684, 74.859000),
    (685, 74.002700),
    (686, 73.146500),
    (687, 72.290200),
    (688, 71.433900),
    (689, 70.577600),
    (690, 69.721300),
    (691, 69.910100),
    (692, 70.098900),
    (693, 70.287600),
    (694, 70.476400),
    (695, 70.665200),
    (696, 70.854000),
    (697, 71.042800),
    (698, 71.231500),
    (699, 71.420300),
    (700, 71.609100),
    (701, 71.883100),
    (702, 72.157100),
    (703, 72.431100),
    (704, 72.705100),
    (705, 72.979000),
    (706, 73.253000),
    (707, 73.527000),
    (708, 73.801000),
    (709, 74.075000),
    (710, 74.349000),
    (711, 73.074500),
    (712, 71.800000),
    (713, 70.525500),
    (714, 69.251000),
    (715, 67.976500),
    (716, 66.702000),
    (717, 65.427500),
    (718, 64.153000),
    (719, 62.878500),
    (720, 61.604000),
    (721, 62.432200),
    (722, 63.260300),
    (723, 64.088500),
    (724, 64.916600),
    (725, 65.744800),
    (726, 66.573000),
    (727, 67.401100),
    (728, 68.229300),
    (729, 69.057400),
    (730, 69.885600),
    (731, 70.405700),
    (732, 70.925900),
    (733, 71.446000),
    (734, 71.966200),
    (735, 72.486300),
    (736, 73.006400),
    (737, 73.526600),
    (738, 74.046700),
    (739, 74.566900),
    (740, 75.087000),
    (741, 73.937600),
    (742, 72.788100),
    (743, 71.638700),
    (744, 70.489300),
    (745, 69.339800),
    (746, 68.190400),
    (747, 67.041000),
    (748, 65.891600),
    (749, 64.742100),
    (750, 63.592700),
    (751, 61.875200),
    (752, 60.157800),
    (753, 58.440300),
    (754, 56.722900),
    (755, 55.005400),
    (756, 53.288000),
    (757, 51.570500),
    (758, 49.853100),
    (759, 48.135600),
    (760, 46.418200),
    (761, 48.456900),
    (762, 50.495600),
    (763, 52.534400),
    (764, 54.573100),
    (765, 56.611800),
    (766, 58.650500),
    (767, 60.689200),
    (768, 62.728000),
    (769, 64.766700),
    (770, 66.805400),
    (771, 66.463100),
    (772, 66.120900),
    (773, 65.778600),
    (774, 65.436400),
    (775, 65.094100),
    (776, 64.751800),
    (777, 64.409600),
    (778, 64.067300),
    (779, 63.725100),
    (780, 63.382800),
    (781, 63.474900),
    (782, 63.567000),
    (783, 63.659200),
    (784, 63.751300),
    (785, 63.843400),
    (786, 63.935500),
    (787, 64.027600),
    (788, 64.119800),
    (789, 64.211900),
    (790, 64.304000),
    (791, 63.818800),
    (792, 63.333600),
    (793, 62.848400),
    (794, 62.363200),
    (795, 61.877900),
    (796, 61.392700),
    (797, 60.907500),
    (798, 60.422300),
    (799, 59.937100),
    (800, 59.451900),
    (801, 58.702600),
    (802, 57.953300),
    (803, 57.204000),
    (804, 56.454700),
    (805, 55.705400),
    (806, 54.956200),
    (807, 54.206900),
    (808, 53.457600),
    (809, 52.708300),
    (810, 51.959000),
    (811, 52.507200),
    (812, 53.055300),
    (813, 53.603500),
    (814, 54.151600),
    (815, 54.699800),
    (816, 55.248000),
    (817, 55.796100),
    (818, 56.344300),
    (819, 56.892400),
    (820, 57.440600),
    (821, 57.727800),
    (822, 58.015000),
    (823, 58.302200),
    (824, 58.589400),
    (825, 58.876500),
    (826, 59.163700),
    (827, 59.450900),
    (828, 59.738100),
    (829, 60.025300),
    (830, 60.312500)
  )
 
  lazy val StandardIlluminants_CIE_D65:CoefficientSpectrum =
    new SampledSpectrum(Illuminantd65.map{i => i._1.toDouble}, Illuminantd65.map{i => i._2},
                        CIE_Interpolation_Mode,
                        100)
}

Re: Scala Swing Grafiken einfügen

2010-09-05T14:59:49+02:00

Evtl. Icon? javax.swing.ImageIcon?
Oder was meinst du mit Bild?

Re: Extention of Enumeration

2010-09-05T13:02:22+02:00

An enumeration is a usual class in Scala.

Language: Scala
scala> class A extends Enumeration {
     | def aMethod(x: Int) = x*x
     | }
defined class A
 
scala> object e extends A {
     | val a, b = Value
     | }
defined module e
 
scala> e.aMethod(2)
res1: Int = 4

closing a dialog; graphics

2010-09-05T11:39:47+02:00

Hi,

how do I close a SimpleSwingApplication or a Frame? dispose() and close() have no effect.

How can I set graphics in a Frame? What is the name of the class?

Extention of Enumeration

2010-09-05T09:34:55+02:00

Hi
Is it possible to add some extra attributes or methods to a scala enum (using the Enumeration class) or not?
THX AG WW

Scala Swing Grafiken einfügen

2010-09-04T11:18:14+02:00

Hallo,

ich habe schon gegoogelt, finde aber nur Themen für Java Swing.

Wie füge ich Bilder in einem Scala Swing Dialog ein?

Ich denke ich mache dies mit

new Label()

und da muss ich dann das Bild übergeben. Aber wie bzw. wie heißt die Klasse dafür?

Re: Java Swing TableLayout

2010-09-04T11:14:54+02:00

Ich bin jetzt über MigLayout gestolpert und verwende das jetzt. Finde es sogar besser als TableLayout. Danke für deine Bemühungen :)

Re: Klassen und Typen

2010-09-03T08:37:30+02:00

Das funktioniert übrigens auch in Java (wenn man auf die statische Typprüfung verzichtet): [dgronau.wordpress.com]

Translations of Scala Books

2010-09-02T22:02:00+02:00

Hello everybody,

Do you know if one of the existing books on scala will be translated in other languages than english ?

I am a french student and I am currently reading the online writing "Programming Scala" of Alex Payne.

However, I prefer reading books in french and I would like to know if one of the scala books will be translated in french, especially "Programming in Scala: A Comprehensive Step-by-step Guide" of Martin Odersky, Lex Spoon, Bill Venners.

Thanks for reply

Re: Klassen und Typen

2010-09-02T18:32:25+02:00

> das funktioniert sowieso nicht weil "*" nicht für
> beliebige Typen definiert ist.

Aber wer hat behauptet, dass man Double & Co. nicht in einer Klasse verpacken kann? Wie z.B.

Language: Scala
trait Scalar {
  type T
  // ....
}
 
class ScalarDouble {
  type U = Double
  overrode type T = U
  // ...
}

Und darauf alles aufbaut?
Das wäre mein Ansatz gewessen, wenn mich Landei nicht etwas besseres belehrt hätte :-)

Re: Klassen und Typen

2010-09-02T18:26:34+02:00

Danke! Echt geil :-)

Re: Klassen und Typen

2010-09-02T09:12:26+02:00

Mit Scalas implicits lassen sich Typklassen (wie in Haskell) simulieren. Für numerische Operationen gibt es schon die fertige "Typklasse" Numeric, die für die üblichen Verdächtigen Int, Long, Double... bereits implementiert ist.

Du kannst aber jederzeit neue Typen über einen implicit-Wert "hinzufügen". Bei der Berechnung liefert nicht der Typ T selbst, sondern "seine" Numeric-Instanz die benötigten Operationen (deshalb das import num._). Du kannst natürlich nur dann ein Test[X]-Objekt instantiieren, wenn auch ein passendes implizites Numeric[X] im Scope ist (hier wäre das PTNum).

Language: Scala
class Test[T](a:T, b:T)(implicit val num:Numeric[T]) {
  def calc = {
    import num._ 
    val c = a + b * a
    c
  }
}
 
case class PossibleType(v:Int) 
 
object TestCalc {
 
  implicit val PTNum:Numeric[PossibleType] = new Numeric[PossibleType] {
    def toDouble(p:PossibleType) = p.v.toDouble
    def toFloat(p:PossibleType) = p.v.toFloat
    def toLong(p:PossibleType) = p.v.toLong
    def toInt(p:PossibleType) = p.v
    def fromInt(i:Int) = PossibleType(i)
    def negate(p:PossibleType) = PossibleType(-p.v)
    def times(a:PossibleType, b:PossibleType) = PossibleType(a.v * b.v)
    def minus(a:PossibleType, b:PossibleType) = PossibleType(a.v - b.v)
    def plus(a:PossibleType, b:PossibleType) = PossibleType(a.v + b.v)
    def compare(a:PossibleType, b:PossibleType) = a.v compare b.v
  }
 
  def main(args:Array[String]) {
    val a = PossibleType(17)
    val b = PossibleType(23)
    println(new Test(a,b).calc)
  } 
 
}

Re: Again Euler, this time Id 14

2010-09-02T00:43:17+02:00

My Code:

Language: Scala
object Problem14 {
  def main(args: Array[String]) {
    def chainLen(i: Long, chain: Int): Int =
      if (i == 1) chain
      else if (i%2 == 0) chainLen(i/2, chain+1)
      else chainLen(3*i+1, chain+1)
    def longestChainNum(end: Int): Int = {
      def loop(i: Int, chain: Int, n: Int): Int =
        if (i < end) {
          val l = chainLen(i, 0)
          if (l > chain) loop(i+1, l, i)
          else loop(i+1, chain, n)
        }
        else n
      loop(1, 0, 0)
    }
    println(longestChainNum(1000000))
  }
}

Re: Klassen und Typen

2010-09-01T22:52:05+02:00

Hallo Thomas,

das funktioniert sowieso nicht weil "*" nicht für beliebige Typen definiert ist.

Language: Scala
scala> class Test[T](a: T, b: T) {
     | def calc = a+b*a
     | }
<console>:6: error: value * is not a member of type parameter T
       def calc = a+b*a
                    ^

Wenn es einen gemeinsamen Typ für numerische Werte gäbe, könnte man den Typparameter entsprechend einschränken, aber soweit ich weiß, gibt es keinen entsprechenden Typ. Evtl. kommst du mit "structural Typing" (static duck typing) weiter.

Klassen und Typen

2010-09-01T21:44:39+02:00

Hallo,

Language: Scala
class Test[T](a:T, b:T) {
  // ...
  def calc = {
    val c = a + b * a
    c
  }
}
 
class PossibleType {
 
  def +(v:PossibleType) = ...
  def * ....
}

Jetzt soll das ganze für T gleich
1. Test[Double], Test[Int], ...
2. Test[PossibleType], Test[...
funktionieren.

Bei 2. sehe ich kein Problem. z.B. würde sich ein trait anbieten. Aber wie schaffe ich es, dass z.B. auch Double geht?

Gruß,
Thomas

Re: Type missmatch

2010-08-31T17:34:48+02:00

If it concerns you, you should respond to the ticket with the requested information. Otherwise, it's going to stay closed.

Randall Schulz

Re: Type missmatch

2010-08-31T16:23:20+02:00

Please test the example which Adriaan Moors gives for more explanation.
And you can see, that something is very strange.

- Barbara

Re: Type missmatch

2010-08-31T16:05:20+02:00

Martin doesn't consider that a bug, as you can see by his reply and his closing that ticket (with "need info", so I suppose it's possible the argument could be made that it is a bug).

Randall Schulz

Re: Again Euler, this time Id 14

2010-08-31T13:25:00+02:00

ramn Wrote:
-------------------------------------------------------
> Did you try enter the starting number?

Hmm, no.
Why didn't I try the starting number? :/
Thank you.

My apologies for making such a fuss.

Manfred

Re: Again Euler, this time Id 14

2010-08-31T13:16:30+02:00

Did you try enter the starting number?

Re: Again Euler, this time Id 14

2010-08-31T13:15:11+02:00

ramn Wrote:
-------------------------------------------------------
> "Which starting number..."

I'm not sure I understand.
Starting number can be any below 1000000 but the longest results probably are expected from 800000 on.

Manfred