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• C# vector class - Interpolation design decision

  - by Benjamin

  Currently I'm working on a vector class in C# and now I'm coming to the point, where I've to figure out, how i want to implement the functions for interpolation between two vectors. At first I came up with implementing the functions directly into the vector class... public class Vector3D { public static Vector3D LinearInterpolate(Vector3D vector1, Vector3D vector2, double factor) { ... } public Vector3D LinearInterpolate(Vector3D other, double factor { ... } } (I always offer both: a static method with two vectors as parameters and one non-static, with only one vector as parameter) ...but then I got the idea to use extension methods (defined in a seperate class called "Interpolation" for example), since interpolation isn't really a thing only available for vectors. So this could be another solution: public class Vector3D { ... } public static class Interpolation { public static Vector3D LinearInterpolate(this Vector3D vector, Vector3D other, double factor) { ... } } So here an example how you'd use the different possibilities: { var vec1 = new Vector3D(5, 3, 1); var vec2 = new Vector3D(4, 2, 0); Vector3D vec3; vec3 = vec1.LinearInterpolate(vec2, 0.5); //1 vec3 = Vector3D.LinearInterpolate(vec1, vec2, 0.5); //2 //or with extension-methods vec3 = vec1.LinearInterpolate(vec2, 0.5); //3 (same as 1) vec3 = Interpolation.LinearInterpolation(vec1, vec2, 0.5); //4 } So I really don't know which design is better. Also I don't know if there's an ultimate rule for things like this or if it's just about what someone personally prefers. But I really would like to hear your opinions, what's better (and if possible why ).

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• Relative encapsulation design

  - by taher1992

  Let's say I am doing a 2D application with the following design: There is the Level object that manages the world, and there are world objects which are entities inside the Level object. A world object has a location and velocity, as well as size and a texture. However, a world object only exposes get properties. The set properties are private (or protected) and are only available to inherited classes. But of course, Level is responsible for these world objects, and must somehow be able to manipulate at least some of its private setters. But as of now, Level has no access, meaning world objects must change its private setters to public (violating encapsulation). How to tackle this problem? Should I just make everything public? Currently what I'm doing is having a inner class inside game object that does the set work. So when Level needs to update an objects location it goes something like this: void ChangeObject(GameObject targetObject, int newX, int newY){ // targetObject.SetX and targetObject.SetY cannot be set directly var setter = new GameObject.Setter(targetObject); setter.SetX(newX); setter.SetY(newY); } This code feels like overkill, but it doesn't feel right to have everything public so that anything can change an objects location for example.

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• design for supporting entities with images

  - by brainydexter

  I have multiple entities like Hotels, Destination Cities etc which can contain images. The way I have my system setup right now is, I think of all the images belonging to this universal set (a table in the DB contains filePaths to all the images). When I have to add an image to an entity, I see if the entity exists in this universal set of images. If it exists, attach the reference to this image, else create a new image. E.g.: class ImageEntityHibernateDAO { public void addImageToEntity(IContainImage entity, String filePath, String title, String altText) { ImageEntity image = this.getImage(filePath); if (image == null) image = new ImageEntity(filePath, title, altText); getSession().beginTransaction(); entity.getImages().add(image); getSession().getTransaction().commit(); } } My question is: Earlier I had to write this code for each entity (and each entity would have a Set collection). So, instead of re-writing the same code, I created the following interface: public interface IContainImage { Set<ImageEntity> getImages(); } Entities which have image collections also implements IContainImage interface. Now, for any entity that needs to support adding Image functionality, all I have to invoke from the DAO looks something like this: // in DestinationDAO::addImageToDestination { imageDao.addImageToEntity(destination, imageFileName, imageTitle, imageAltText); // in HotelDAO::addImageToHotel { imageDao.addImageToEntity(hotel, imageFileName, imageTitle, imageAltText); It'd be great help if someone can provide me some critique on this design ? Are there any serious flaws that I'm not seeing right away ?

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• Best Design Pattern for Coupling User Interface Components and Data Structures

  - by szahn

  I have a windows desktop application with a tree view. Due to lack of a sound data-binding solution for a tree view, I've implemented my own layer of abstraction on it to bind nodes to my own data structure. The requirements are as follows: Populate a tree view with nodes that resemble fields in a data structure. When a node is clicked, display the appropriate control to modify the value of that property in the instance of the data structure. The tree view is populated with instances of custom TreeNode classes that inherit from TreeNode. The responsibility of each custom TreeNode class is to (1) format the node text to represent the name and value of the associated field in my data structure, (2) return the control used to modify the property value, (3) get the value of the field in the control (3) set the field's value from the control. My custom TreeNode implementation has a property called "Control" which retrieves the proper custom control in the form of the base control. The control instance is stored in the custom node and instantiated upon first retrieval. So each, custom node has an associated custom control which extends a base abstract control class. Example TreeNode implementation: //The Tree Node Base Class public abstract class TreeViewNodeBase : TreeNode { public abstract CustomControlBase Control { get; } public TreeViewNodeBase(ExtractionField field) { UpdateControl(field); } public virtual void UpdateControl(ExtractionField field) { Control.UpdateControl(field); UpdateCaption(FormatValueForCaption()); } public virtual void SaveChanges(ExtractionField field) { Control.SaveChanges(field); UpdateCaption(FormatValueForCaption()); } public virtual string FormatValueForCaption() { return Control.FormatValueForCaption(); } public virtual void UpdateCaption(string newValue) { this.Text = Caption; this.LongText = newValue; } } //The tree node implementation class public class ExtractionTypeNode : TreeViewNodeBase { private CustomDropDownControl control; public override CustomControlBase Control { get { if (control == null) { control = new CustomDropDownControl(); control.label1.Text = Caption; control.comboBox1.Items.Clear(); control.comboBox1.Items.AddRange( Enum.GetNames( typeof(ExtractionField.ExtractionType))); } return control; } } public ExtractionTypeNode(ExtractionField field) : base(field) { } } //The custom control base class public abstract class CustomControlBase : UserControl { public abstract void UpdateControl(ExtractionField field); public abstract void SaveChanges(ExtractionField field); public abstract string FormatValueForCaption(); } //The custom control generic implementation (view) public partial class CustomDropDownControl : CustomControlBase { public CustomDropDownControl() { InitializeComponent(); } public override void UpdateControl(ExtractionField field) { //Nothing to do here } public override void SaveChanges(ExtractionField field) { //Nothing to do here } public override string FormatValueForCaption() { //Nothing to do here return string.Empty; } } //The custom control specific implementation public class FieldExtractionTypeControl : CustomDropDownControl { public override void UpdateControl(ExtractionField field) { comboBox1.SelectedIndex = comboBox1.FindStringExact(field.Extraction.ToString()); } public override void SaveChanges(ExtractionField field) { field.Extraction = (ExtractionField.ExtractionType) Enum.Parse(typeof(ExtractionField.ExtractionType), comboBox1.SelectedItem.ToString()); } public override string FormatValueForCaption() { return string.Empty; } The problem is that I have "generic" controls which inherit from CustomControlBase. These are just "views" with no logic. Then I have specific controls that inherit from the generic controls. I don't have any functions or business logic in the generic controls because the specific controls should govern how data is associated with the data structure. What is the best design pattern for this?

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• Designer issue in VS: Events cannot be set on the object passed to the event binding service ...

  - by serhio

  I have a little problem: the Winform control (that contains between others WPF) suddenly stopped to be displayed in Designer. Message: Events cannot be set on the object passed to the event binding service because a site associated with the object could not be located. Call Stack: at System.ComponentModel.Design.EventBindingService.EventPropertyDescriptor.SetValue(Object component, Object value) at System.ComponentModel.Design.Serialization.CodeDomSerializerBase.DeserializeAttachEventStatement(IDesignerSerializationManager manager, CodeAttachEventStatement statement) at System.ComponentModel.Design.Serialization.CodeDomSerializerBase.DeserializeStatement(IDesignerSerializationManager manager, CodeStatement statement) Where could be the problem? InitializeComponent code Private Sub InitializeComponent() Dim resources As System.ComponentModel.ComponentResourceManager = New System.ComponentModel.ComponentResourceManager(GetType(PlanDeLigne)) Dim Appearance1 As Infragistics.Win.Appearance = New Infragistics.Win.Appearance() Dim Appearance2 As Infragistics.Win.Appearance = New Infragistics.Win.Appearance() Dim Appearance3 As Infragistics.Win.Appearance = New Infragistics.Win.Appearance() Dim Appearance4 As Infragistics.Win.Appearance = New Infragistics.Win.Appearance() Dim Appearance5 As Infragistics.Win.Appearance = New Infragistics.Win.Appearance() Dim Appearance6 As Infragistics.Win.Appearance = New Infragistics.Win.Appearance() Dim Appearance7 As Infragistics.Win.Appearance = New Infragistics.Win.Appearance() Dim Appearance8 As Infragistics.Win.Appearance = New Infragistics.Win.Appearance() Dim Appearance9 As Infragistics.Win.Appearance = New Infragistics.Win.Appearance() Dim Appearance10 As Infragistics.Win.Appearance = New Infragistics.Win.Appearance() Dim Appearance11 As Infragistics.Win.Appearance = New Infragistics.Win.Appearance() Dim Appearance12 As Infragistics.Win.Appearance = New Infragistics.Win.Appearance() Me.mnbMenu = New System.Windows.Forms.ToolStrip() Me.mncMode = New System.Windows.Forms.ToolStripComboBox() Me.mnbSeparator1 = New System.Windows.Forms.ToolStripSeparator() Me.mnbAdd = New System.Windows.Forms.ToolStripButton() Me.mnbDelete = New System.Windows.Forms.ToolStripButton() Me.mnbSeparator2 = New System.Windows.Forms.ToolStripSeparator() Me.mnbDropDownAction = New System.Windows.Forms.ToolStripDropDownButton() Me.mnbDropDownActionSens = New System.Windows.Forms.ToolStripMenuItem() Me.mnbDropDownActionSeparator1 = New System.Windows.Forms.ToolStripSeparator() Me.mnbDropDownActionDistances = New System.Windows.Forms.ToolStripMenuItem() Me.mnbDropDownActionSeparator2 = New System.Windows.Forms.ToolStripSeparator() Me.mnbDropDownActionArretsPhysiques = New System.Windows.Forms.ToolStripMenuItem() Me.mnbSeparator3 = New System.Windows.Forms.ToolStripSeparator() Me.mnbSelectionZoom = New System.Windows.Forms.ToolStripButton() Me.mnbCancelZoom = New System.Windows.Forms.ToolStripButton() Me.mnbSeparator4 = New System.Windows.Forms.ToolStripSeparator() Me.mnbParametrage = New System.Windows.Forms.ToolStripButton() Me.mncSPlacerArret = New System.Windows.Forms.ToolStripMenuItem() Me.mncSSeparator1 = New System.Windows.Forms.ToolStripSeparator() Me.mncSImage = New System.Windows.Forms.ToolStripMenuItem() Me.mncSDefinirLastArret = New System.Windows.Forms.ToolStripMenuItem() Me.mncSSeparator2 = New System.Windows.Forms.ToolStripSeparator() Me.mncSSupprimerArrets = New System.Windows.Forms.ToolStripMenuItem() Me.mncSInsererArret = New System.Windows.Forms.ToolStripMenuItem() Me.mncSSeparator3 = New System.Windows.Forms.ToolStripSeparator() Me.mncSInformations = New System.Windows.Forms.ToolStripMenuItem() Me.mncSSupprimerSegment = New System.Windows.Forms.ToolStripMenuItem() Me.mncSSeparator4 = New System.Windows.Forms.ToolStripSeparator() Me.mncSBatirTroncon = New System.Windows.Forms.ToolStripMenuItem() Me.mncTInformations = New System.Windows.Forms.ToolStripMenuItem() Me.mncTDistances = New System.Windows.Forms.ToolStripMenuItem() Me.mncTSeparator1 = New System.Windows.Forms.ToolStripSeparator() Me.mncTTempsDeParcours = New System.Windows.Forms.ToolStripMenuItem() Me.mncTSeparator2 = New System.Windows.Forms.ToolStripSeparator() Me.mncTCreerSensInverse = New System.Windows.Forms.ToolStripMenuItem() Me.mncTSeparator3 = New System.Windows.Forms.ToolStripSeparator() Me.mncTSupprimerTroncon = New System.Windows.Forms.ToolStripMenuItem() Me.mncTBatirItineraire = New System.Windows.Forms.ToolStripMenuItem() Me.mncIInformations = New System.Windows.Forms.ToolStripMenuItem() Me.mncISeparator1 = New System.Windows.Forms.ToolStripSeparator() Me.mncISupprimerItineraire = New System.Windows.Forms.ToolStripMenuItem() Me.SplitContainer = New System.Windows.Forms.SplitContainer() Me.ElementHost1 = New System.Windows.Forms.Integration.ElementHost() Me._StopsCanvas = New Keolis.ctlWpfPlanDeLigne.StopsCanvas() Me.lblTitreCreation = New Keolis.ctlComponents.Label() Me.Panel1 = New System.Windows.Forms.Panel() Me.btnOk = New Keolis.ctlComponents.Button() Me.btnAnnuler = New Keolis.ctlComponents.Button() Me.grdCreation = New Keolis.ctlWinGrid.WinGrid() Me.mnbMenu.SuspendLayout() CType(Me.SplitContainer, System.ComponentModel.ISupportInitialize).BeginInit() Me.SplitContainer.Panel1.SuspendLayout() Me.SplitContainer.Panel2.SuspendLayout() Me.SplitContainer.SuspendLayout() Me.Panel1.SuspendLayout() CType(Me.grdCreation, System.ComponentModel.ISupportInitialize).BeginInit() Me.SuspendLayout() ' 'mnbMenu ' Me.mnbMenu.GripStyle = System.Windows.Forms.ToolStripGripStyle.Hidden Me.mnbMenu.Items.AddRange(New System.Windows.Forms.ToolStripItem() {Me.mncMode, Me.mnbSeparator1, Me.mnbAdd, Me.mnbDelete, Me.mnbSeparator2, Me.mnbDropDownAction, Me.mnbSeparator3, Me.mnbSelectionZoom, Me.mnbCancelZoom, Me.mnbSeparator4, Me.mnbParametrage}) Me.mnbMenu.Location = New System.Drawing.Point(0, 0) Me.mnbMenu.Name = "mnbMenu" Me.mnbMenu.Size = New System.Drawing.Size(605, 25) Me.mnbMenu.TabIndex = 2 ' 'mncMode ' Me.mncMode.DropDownStyle = System.Windows.Forms.ComboBoxStyle.DropDownList Me.mncMode.Name = "mncMode" Me.mncMode.Size = New System.Drawing.Size(121, 25) Me.mncMode.ToolTipText = "Mode du plan de ligne" ' 'mnbSeparator1 ' Me.mnbSeparator1.AutoSize = False Me.mnbSeparator1.Name = "mnbSeparator1" Me.mnbSeparator1.Size = New System.Drawing.Size(20, 25) ' 'mnbAdd ' Me.mnbAdd.DisplayStyle = System.Windows.Forms.ToolStripItemDisplayStyle.Image Me.mnbAdd.Image = CType(resources.GetObject("mnbAdd.Image"), System.Drawing.Image) Me.mnbAdd.ImageTransparentColor = System.Drawing.Color.Magenta Me.mnbAdd.Name = "mnbAdd" Me.mnbAdd.Size = New System.Drawing.Size(23, 22) Me.mnbAdd.Text = "Création Tronçon / Itinéraire" ' 'mnbDelete ' Me.mnbDelete.DisplayStyle = System.Windows.Forms.ToolStripItemDisplayStyle.Image Me.mnbDelete.Image = CType(resources.GetObject("mnbDelete.Image"), System.Drawing.Image) Me.mnbDelete.ImageTransparentColor = System.Drawing.Color.Magenta Me.mnbDelete.Name = "mnbDelete" Me.mnbDelete.Size = New System.Drawing.Size(23, 22) Me.mnbDelete.Text = "Supprimer les éléments sélectionnés" ' 'mnbSeparator2 ' Me.mnbSeparator2.AutoSize = False Me.mnbSeparator2.Name = "mnbSeparator2" Me.mnbSeparator2.Size = New System.Drawing.Size(20, 25) ' 'mnbDropDownAction ' Me.mnbDropDownAction.DisplayStyle = System.Windows.Forms.ToolStripItemDisplayStyle.Image Me.mnbDropDownAction.DropDownItems.AddRange(New System.Windows.Forms.ToolStripItem() {Me.mnbDropDownActionSens, Me.mnbDropDownActionSeparator1, Me.mnbDropDownActionDistances, Me.mnbDropDownActionSeparator2, Me.mnbDropDownActionArretsPhysiques}) Me.mnbDropDownAction.Image = CType(resources.GetObject("mnbDropDownAction.Image"), System.Drawing.Image) Me.mnbDropDownAction.ImageTransparentColor = System.Drawing.Color.Magenta Me.mnbDropDownAction.Name = "mnbDropDownAction" Me.mnbDropDownAction.Size = New System.Drawing.Size(29, 22) Me.mnbDropDownAction.Text = "Action sur le plan de ligne" ' 'mnbDropDownActionSens ' Me.mnbDropDownActionSens.Checked = True Me.mnbDropDownActionSens.CheckOnClick = True Me.mnbDropDownActionSens.CheckState = System.Windows.Forms.CheckState.Checked Me.mnbDropDownActionSens.Name = "mnbDropDownActionSens" Me.mnbDropDownActionSens.Size = New System.Drawing.Size(222, 22) Me.mnbDropDownActionSens.Text = "Afficher le sens" ' 'mnbDropDownActionSeparator1 ' Me.mnbDropDownActionSeparator1.Name = "mnbDropDownActionSeparator1" Me.mnbDropDownActionSeparator1.Size = New System.Drawing.Size(219, 6) ' 'mnbDropDownActionDistances ' Me.mnbDropDownActionDistances.Checked = True Me.mnbDropDownActionDistances.CheckOnClick = True Me.mnbDropDownActionDistances.CheckState = System.Windows.Forms.CheckState.Checked Me.mnbDropDownActionDistances.Name = "mnbDropDownActionDistances" Me.mnbDropDownActionDistances.Size = New System.Drawing.Size(222, 22) Me.mnbDropDownActionDistances.Text = "Afficher les distances" ' 'mnbDropDownActionSeparator2 ' Me.mnbDropDownActionSeparator2.Name = "mnbDropDownActionSeparator2" Me.mnbDropDownActionSeparator2.Size = New System.Drawing.Size(219, 6) ' 'mnbDropDownActionArretsPhysiques ' Me.mnbDropDownActionArretsPhysiques.Checked = True Me.mnbDropDownActionArretsPhysiques.CheckOnClick = True Me.mnbDropDownActionArretsPhysiques.CheckState = System.Windows.Forms.CheckState.Checked Me.mnbDropDownActionArretsPhysiques.Name = "mnbDropDownActionArretsPhysiques" Me.mnbDropDownActionArretsPhysiques.Size = New System.Drawing.Size(222, 22) Me.mnbDropDownActionArretsPhysiques.Text = "Afficher les arrêts physiques" ' 'mnbSeparator3 ' Me.mnbSeparator3.AutoSize = False Me.mnbSeparator3.Name = "mnbSeparator3" Me.mnbSeparator3.Size = New System.Drawing.Size(20, 25) ' 'mnbSelectionZoom ' Me.mnbSelectionZoom.CheckOnClick = True Me.mnbSelectionZoom.DisplayStyle = System.Windows.Forms.ToolStripItemDisplayStyle.Image Me.mnbSelectionZoom.Image = CType(resources.GetObject("mnbSelectionZoom.Image"), System.Drawing.Image) Me.mnbSelectionZoom.ImageTransparentColor = System.Drawing.Color.Magenta Me.mnbSelectionZoom.Name = "mnbSelectionZoom" Me.mnbSelectionZoom.Size = New System.Drawing.Size(23, 22) Me.mnbSelectionZoom.Text = "Zoom par sélection" ' 'mnbCancelZoom ' Me.mnbCancelZoom.DisplayStyle = System.Windows.Forms.ToolStripItemDisplayStyle.Image Me.mnbCancelZoom.Image = CType(resources.GetObject("mnbCancelZoom.Image"), System.Drawing.Image) Me.mnbCancelZoom.ImageTransparentColor = System.Drawing.Color.Magenta Me.mnbCancelZoom.Name = "mnbCancelZoom" Me.mnbCancelZoom.Size = New System.Drawing.Size(23, 22) Me.mnbCancelZoom.Text = "Annuler le zoom" ' 'mnbSeparator4 ' Me.mnbSeparator4.AutoSize = False Me.mnbSeparator4.Name = "mnbSeparator4" Me.mnbSeparator4.Size = New System.Drawing.Size(20, 25) ' 'mnbParametrage ' Me.mnbParametrage.DisplayStyle = System.Windows.Forms.ToolStripItemDisplayStyle.Image Me.mnbParametrage.Image = CType(resources.GetObject("mnbParametrage.Image"), System.Drawing.Image) Me.mnbParametrage.ImageTransparentColor = System.Drawing.Color.Magenta Me.mnbParametrage.Name = "mnbParametrage" Me.mnbParametrage.Size = New System.Drawing.Size(23, 22) Me.mnbParametrage.Text = "Paramétrage" ' 'mncSPlacerArret ' Me.mncSPlacerArret.Name = "mncSPlacerArret" Me.mncSPlacerArret.Size = New System.Drawing.Size(216, 22) Me.mncSPlacerArret.Text = "Placer un arrêt" ' 'mncSSeparator1 ' Me.mncSSeparator1.Name = "mncSSeparator1" Me.mncSSeparator1.Size = New System.Drawing.Size(213, 6) ' 'mncSImage ' Me.mncSImage.Name = "mncSImage" Me.mncSImage.Size = New System.Drawing.Size(216, 22) Me.mncSImage.Text = "Image..." ' 'mncSDefinirLastArret ' Me.mncSDefinirLastArret.Name = "mncSDefinirLastArret" Me.mncSDefinirLastArret.Size = New System.Drawing.Size(216, 22) Me.mncSDefinirLastArret.Text = "Définir comme dernier arrêt" ' 'mncSSeparator2 ' Me.mncSSeparator2.Name = "mncSSeparator2" Me.mncSSeparator2.Size = New System.Drawing.Size(213, 6) ' 'mncSSupprimerArrets ' Me.mncSSupprimerArrets.Name = "mncSSupprimerArrets" Me.mncSSupprimerArrets.Size = New System.Drawing.Size(216, 22) Me.mncSSupprimerArrets.Text = "Supprimer le ou les arrêts" ' 'mncSInsererArret ' Me.mncSInsererArret.Name = "mncSInsererArret" Me.mncSInsererArret.Size = New System.Drawing.Size(216, 22) Me.mncSInsererArret.Text = "Insérer un arrêt" ' 'mncSSeparator3 ' Me.mncSSeparator3.Name = "mncSSeparator3" Me.mncSSeparator3.Size = New System.Drawing.Size(213, 6) ' 'mncSInformations ' Me.mncSInformations.Name = "mncSInformations" Me.mncSInformations.Size = New System.Drawing.Size(216, 22) Me.mncSInformations.Text = "Modifier les informations" ' 'mncSSupprimerSegment ' Me.mncSSupprimerSegment.Name = "mncSSupprimerSegment" Me.mncSSupprimerSegment.Size = New System.Drawing.Size(216, 22) Me.mncSSupprimerSegment.Text = "Supprimer le segment" ' 'mncSSeparator4 ' Me.mncSSeparator4.Name = "mncSSeparator4" Me.mncSSeparator4.Size = New System.Drawing.Size(213, 6) ' 'mncSBatirTroncon ' Me.mncSBatirTroncon.Name = "mncSBatirTroncon" Me.mncSBatirTroncon.Size = New System.Drawing.Size(216, 22) Me.mncSBatirTroncon.Text = "Bâtir un tronçon" ' 'mncTInformations ' Me.mncTInformations.Name = "mncTInformations" Me.mncTInformations.Size = New System.Drawing.Size(201, 22) Me.mncTInformations.Text = "Modifier les informations" ' 'mncTDistances ' Me.mncTDistances.Name = "mncTDistances" Me.mncTDistances.Size = New System.Drawing.Size(201, 22) Me.mncTDistances.Text = "Modifier les distances" ' 'mncTSeparator1 ' Me.mncTSeparator1.Name = "mncTSeparator1" Me.mncTSeparator1.Size = New System.Drawing.Size(198, 6) ' 'mncTTempsDeParcours ' Me.mncTTempsDeParcours.Name = "mncTTempsDeParcours" Me.mncTTempsDeParcours.Size = New System.Drawing.Size(201, 22) Me.mncTTempsDeParcours.Text = "Temps de parcours" ' 'mncTSeparator2 ' Me.mncTSeparator2.Name = "mncTSeparator2" Me.mncTSeparator2.Size = New System.Drawing.Size(198, 6) ' 'mncTCreerSensInverse ' Me.mncTCreerSensInverse.Name = "mncTCreerSensInverse" Me.mncTCreerSensInverse.Size = New System.Drawing.Size(201, 22) Me.mncTCreerSensInverse.Text = "Créer le sens inverse" ' 'mncTSeparator3 ' Me.mncTSeparator3.Name = "mncTSeparator3" Me.mncTSeparator3.Size = New System.Drawing.Size(198, 6) ' 'mncTSupprimerTroncon ' Me.mncTSupprimerTroncon.Name = "mncTSupprimerTroncon" Me.mncTSupprimerTroncon.Size = New System.Drawing.Size(201, 22) Me.mncTSupprimerTroncon.Text = "Supprimer le tronçon" ' 'mncTBatirItineraire ' Me.mncTBatirItineraire.Name = "mncTBatirItineraire" Me.mncTBatirItineraire.Size = New System.Drawing.Size(201, 22) Me.mncTBatirItineraire.Text = "Bâtir un itinéraire" ' 'mncIInformations ' Me.mncIInformations.Name = "mncIInformations" Me.mncIInformations.Size = New System.Drawing.Size(201, 22) Me.mncIInformations.Text = "Modifier les informations" ' 'mncISeparator1 ' Me.mncISeparator1.Name = "mncISeparator1" Me.mncISeparator1.Size = New System.Drawing.Size(198, 6) ' 'mncISupprimerItineraire ' Me.mncISupprimerItineraire.Name = "mncISupprimerItineraire" Me.mncISupprimerItineraire.Size = New System.Drawing.Size(201, 22) Me.mncISupprimerItineraire.Text = "Supprimer l'itinéraires" ' 'SplitContainer ' Me.SplitContainer.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D Me.SplitContainer.Dock = System.Windows.Forms.DockStyle.Fill Me.SplitContainer.FixedPanel = System.Windows.Forms.FixedPanel.Panel2 Me.SplitContainer.Location = New System.Drawing.Point(0, 25) Me.SplitContainer.Name = "SplitContainer" ' 'SplitContainer.Panel1 ' Me.SplitContainer.Panel1.AutoScroll = True Me.SplitContainer.Panel1.Controls.Add(Me.ElementHost1) ' 'SplitContainer.Panel2 ' Me.SplitContainer.Panel2.Controls.Add(Me.lblTitreCreation) Me.SplitContainer.Panel2.Controls.Add(Me.Panel1) Me.SplitContainer.Panel2.Controls.Add(Me.grdCreation) Me.SplitContainer.Panel2MinSize = 0 Me.SplitContainer.Size = New System.Drawing.Size(605, 418) Me.SplitContainer.SplitterDistance = 428 Me.SplitContainer.SplitterWidth = 2 Me.SplitContainer.TabIndex = 1 ' 'ElementHost1 ' Me.ElementHost1.Dock = System.Windows.Forms.DockStyle.Fill Me.ElementHost1.Location = New System.Drawing.Point(0, 0) Me.ElementHost1.Name = "ElementHost1" Me.ElementHost1.Size = New System.Drawing.Size(424, 414) Me.ElementHost1.TabIndex = 0 Me.ElementHost1.Text = "ElementHost1" Me.ElementHost1.Child = Me._StopsCanvas ' 'lblTitreCreation ' Me.lblTitreCreation.Anchor = CType(((System.Windows.Forms.AnchorStyles.Top Or System.Windows.Forms.AnchorStyles.Left) _ Or System.Windows.Forms.AnchorStyles.Right), System.Windows.Forms.AnchorStyles) Me.lblTitreCreation.Location = New System.Drawing.Point(3, 4) Me.lblTitreCreation.Name = "lblTitreCreation" Me.lblTitreCreation.Size = New System.Drawing.Size(167, 16) Me.lblTitreCreation.TabIndex = 4 ' 'Panel1 ' Me.Panel1.AutoSize = True Me.Panel1.AutoSizeMode = System.Windows.Forms.AutoSizeMode.GrowAndShrink Me.Panel1.Controls.Add(Me.btnOk) Me.Panel1.Controls.Add(Me.btnAnnuler) Me.Panel1.Dock = System.Windows.Forms.DockStyle.Bottom Me.Panel1.Location = New System.Drawing.Point(0, 385) Me.Panel1.Name = "Panel1" Me.Panel1.Size = New System.Drawing.Size(171, 29) Me.Panel1.TabIndex = 3 ' 'btnOk ' Me.btnOk.Anchor = CType((System.Windows.Forms.AnchorStyles.Top Or System.Windows.Forms.AnchorStyles.Right), System.Windows.Forms.AnchorStyles) Me.btnOk.BackColor = System.Drawing.SystemColors.Control Me.btnOk.FlatAppearance.MouseDownBackColor = System.Drawing.Color.LightSlateGray Me.btnOk.FlatAppearance.MouseOverBackColor = System.Drawing.Color.LightSteelBlue Me.btnOk.FlatStyle = System.Windows.Forms.FlatStyle.Flat Me.btnOk.Font = New System.Drawing.Font("Microsoft Sans Serif", 8.25!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte)) Me.btnOk.ForeColor = System.Drawing.SystemColors.ControlText Me.btnOk.Location = New System.Drawing.Point(12, 3) Me.btnOk.Name = "btnOk" Me.btnOk.Size = New System.Drawing.Size(75, 23) Me.btnOk.TabIndex = 6 Me.btnOk.Text = "OK" Me.btnOk.UseVisualStyleBackColor = True ' 'btnAnnuler ' Me.btnAnnuler.Anchor = CType((System.Windows.Forms.AnchorStyles.Top Or System.Windows.Forms.AnchorStyles.Right), System.Windows.Forms.AnchorStyles) Me.btnAnnuler.BackColor = System.Drawing.SystemColors.Control Me.btnAnnuler.DialogResult = System.Windows.Forms.DialogResult.Cancel Me.btnAnnuler.FlatAppearance.MouseDownBackColor = System.Drawing.Color.LightSlateGray Me.btnAnnuler.FlatAppearance.MouseOverBackColor = System.Drawing.Color.LightSteelBlue Me.btnAnnuler.FlatStyle = System.Windows.Forms.FlatStyle.Flat Me.btnAnnuler.Font = New System.Drawing.Font("Microsoft Sans Serif", 8.25!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte)) Me.btnAnnuler.ForeColor = System.Drawing.SystemColors.ControlText Me.btnAnnuler.Location = New System.Drawing.Point(93, 3) Me.btnAnnuler.Name = "btnAnnuler" Me.btnAnnuler.Size = New System.Drawing.Size(75, 23) Me.btnAnnuler.TabIndex = 7 Me.btnAnnuler.Text = "Annuler" Me.btnAnnuler.UseVisualStyleBackColor = True ' 'grdCreation ' Me.grdCreation.Anchor = CType((((System.Windows.Forms.AnchorStyles.Top Or System.Windows.Forms.AnchorStyles.Bottom) _ Or System.Windows.Forms.AnchorStyles.Left) _ Or System.Windows.Forms.AnchorStyles.Right), System.Windows.Forms.AnchorStyles) Me.grdCreation.AutoResizeColumns = False Me.grdCreation.ColumnsFiltreActif = False Appearance1.BackColor = System.Drawing.SystemColors.Window Appearance1.BorderColor = System.Drawing.SystemColors.InactiveCaption Me.grdCreation.DisplayLayout.Appearance = Appearance1 Me.grdCreation.DisplayLayout.BorderStyle = Infragistics.Win.UIElementBorderStyle.Solid Me.grdCreation.DisplayLayout.CaptionVisible = Infragistics.Win.DefaultableBoolean.[False] Appearance2.BackColor = System.Drawing.SystemColors.ActiveBorder Appearance2.BackColor2 = System.Drawing.SystemColors.ControlDark Appearance2.BackGradientStyle = Infragistics.Win.GradientStyle.Vertical Appearance2.BorderColor = System.Drawing.SystemColors.Window Me.grdCreation.DisplayLayout.GroupByBox.Appearance = Appearance2 Appearance3.ForeColor = System.Drawing.SystemColors.GrayText Me.grdCreation.DisplayLayout.GroupByBox.BandLabelAppearance = Appearance3 Me.grdCreation.DisplayLayout.GroupByBox.BorderStyle = Infragistics.Win.UIElementBorderStyle.Solid Appearance4.BackColor = System.Drawing.SystemColors.ControlLightLight Appearance4.BackColor2 = System.Drawing.SystemColors.Control Appearance4.BackGradientStyle = Infragistics.Win.GradientStyle.Horizontal Appearance4.ForeColor = System.Drawing.SystemColors.GrayText Me.grdCreation.DisplayLayout.GroupByBox.PromptAppearance = Appearance4 Me.grdCreation.DisplayLayout.MaxColScrollRegions = 1 Me.grdCreation.DisplayLayout.MaxRowScrollRegions = 1 Appearance5.BackColor = System.Drawing.SystemColors.Window Appearance5.ForeColor = System.Drawing.SystemColors.ControlText Me.grdCreation.DisplayLayout.Override.ActiveCellAppearance = Appearance5 Appearance6.BackColor = System.Drawing.SystemColors.Highlight Appearance6.ForeColor = System.Drawing.SystemColors.HighlightText Me.grdCreation.DisplayLayout.Override.ActiveRowAppearance = Appearance6 Me.grdCreation.DisplayLayout.Override.AllowRowFiltering = Infragistics.Win.DefaultableBoolean.[False] Me.grdCreation.DisplayLayout.Override.BorderStyleCell = Infragistics.Win.UIElementBorderStyle.Dotted Me.grdCreation.DisplayLayout.Override.BorderStyleRow = Infragistics.Win.UIElementBorderStyle.Dotted Appearance7.BackColor = System.Drawing.SystemColors.Window Me.grdCreation.DisplayLayout.Override.CardAreaAppearance = Appearance7 Appearance8.BorderColor = System.Drawing.Color.Silver Appearance8.TextTrimming = Infragistics.Win.TextTrimming.EllipsisCharacter Me.grdCreation.DisplayLayout.Override.CellAppearance = Appearance8 Me.grdCreation.DisplayLayout.Override.CellPadding = 0 Appearance9.BackColor = System.Drawing.SystemColors.Control Appearance9.BackColor2 = System.Drawing.SystemColors.ControlDark Appearance9.BackGradientAlignment = Infragistics.Win.GradientAlignment.Element Appearance9.BackGradientStyle = Infragistics.Win.GradientStyle.Horizontal Appearance9.BorderColor = System.Drawing.SystemColors.Window Me.grdCreation.DisplayLayout.Override.GroupByRowAppearance = Appearance9 Appearance10.TextHAlignAsString = "Left" Me.grdCreation.DisplayLayout.Override.HeaderAppearance = Appearance10 Me.grdCreation.DisplayLayout.Override.HeaderClickAction = Infragistics.Win.UltraWinGrid.HeaderClickAction.SortMulti Me.grdCreation.DisplayLayout.Override.HeaderStyle = Infragistics.Win.HeaderStyle.WindowsXPCommand Appearance11.BackColor = System.Drawing.SystemColors.Window Appearance11.BorderColor = System.Drawing.Color.Silver Me.grdCreation.DisplayLayout.Override.RowAppearance = Appearance11 Me.grdCreation.DisplayLayout.Override.RowSelectors = Infragistics.Win.DefaultableBoolean.[False] Appearance12.BackColor = System.Drawing.SystemColors.ControlLight Me.grdCreation.DisplayLayout.Override.TemplateAddRowAppearance = Appearance12 Me.grdCreation.DisplayLayout.ScrollBounds = Infragistics.Win.UltraWinGrid.ScrollBounds.ScrollToFill Me.grdCreation.DisplayLayout.ScrollStyle = Infragistics.Win.UltraWinGrid.ScrollStyle.Immediate Me.grdCreation.DisplayLayout.ViewStyleBand = Infragistics.Win.UltraWinGrid.ViewStyleBand.OutlookGroupBy Me.grdCreation.Font = New System.Drawing.Font("Times New Roman", 8.25!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte)) Me.grdCreation.Location = New System.Drawing.Point(0, 23) Me.grdCreation.Name = "grdCreation" Me.grdCreation.PrintColumnsKey = Nothing Me.grdCreation.PrintRowsIndex = Nothing Me.grdCreation.PrintTitle = Nothing Me.grdCreation.RowsActivation = Infragistics.Win.UltraWinGrid.Activation.AllowEdit Me.grdCreation.Size = New System.Drawing.Size(175, 391) Me.grdCreation.TabIndex = 5 Me.grdCreation.Tag = "" ' 'PlanDeLigne ' Me.AutoScaleDimensions = New System.Drawing.SizeF(6.0!, 13.0!) Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font Me.Controls.Add(Me.SplitContainer) Me.Controls.Add(Me.mnbMenu) Me.MinimumSize = New System.Drawing.Size(605, 431) Me.Name = "PlanDeLigne" Me.Size = New System.Drawing.Size(605, 443) Me.mnbMenu.ResumeLayout(False) Me.mnbMenu.PerformLayout() Me.SplitContainer.Panel1.ResumeLayout(False) Me.SplitContainer.Panel2.ResumeLayout(False) Me.SplitContainer.Panel2.PerformLayout() CType(Me.SplitContainer, System.ComponentModel.ISupportInitialize).EndInit() Me.SplitContainer.ResumeLayout(False) Me.Panel1.ResumeLayout(False) CType(Me.grdCreation, System.ComponentModel.ISupportInitialize).EndInit() Me.ResumeLayout(False) Me.PerformLayout() End Sub

  Read the article

• HttpClient POST fails to submit the form

  - by Jayomat

  Hi, I'm writing an app to check for the bus timetable's. Therefor I need to post some data to a html page, submit it, and parse the resulting page with htmlparser. Though it may be asked a lot, can some one help me identify if 1) this page does support post/get (I think it does) 2) which fields I need to use? 3) How to make the actual request? this is my code so far: String url = "http://busspur02.aseag.de/bs.exe?Cmd=RV&Karten=true&DatumT=30&DatumM=4&DatumJ=2010&ZeitH=&ZeitM=&Suchen=%28S%29uchen&GT0=&HT0=&GT1=&HT1="; String charset = "CP1252"; System.out.println("startFrom: "+start_from); System.out.println("goTo: "+destination); //String tag.v List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("HTO", start_from)); params.add(new BasicNameValuePair("HT1", destination)); params.add(new BasicNameValuePair("GTO", "Aachen")); params.add(new BasicNameValuePair("GT1", "Aachen")); params.add(new BasicNameValuePair("DatumT", day)); params.add(new BasicNameValuePair("DatumM", month)); params.add(new BasicNameValuePair("DatumJ", year)); params.add(new BasicNameValuePair("ZeitH", hour)); params.add(new BasicNameValuePair("ZeitM", min)); UrlEncodedFormEntity query = new UrlEncodedFormEntity(params, charset); HttpPost post = new HttpPost(url); post.setEntity(query); InputStream response = new DefaultHttpClient().execute(post).getEntity().getContent(); // Now do your thing with the facebook response. String source = readText(response,"CP1252"); Log.d(TAG_AVV,response.toString()); System.out.println("STREAM "+source); One person also gave me a hint to use firebug to read what's going on at the page, but I don't really understand what to look for, or more precisely, how to use the provided information. I also find it confusing, for example, that when I enter the data by hand, the url says, for example, "....HTO=Kaiserplatz&...", but in Firebug, the same Kaiserplatz is connected to a different field, in this case: \<\td class="Start3" Kaiserplatz <\/td (I inserted \ to make it visible) The last line in my code prints the html page, but without having send a request.. it's printed as if there was no input at all... My app is almost done, I hope someone can help me out to finish it! thanks in advance EDIT: this is what the s.o.p returns: (At some point there actually is some input, but only the destination ???) 04-30 03:15:43.524: INFO/System.out(3303): STREAM <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 04-30 03:15:43.524: INFO/System.out(3303): <html> 04-30 03:15:43.524: INFO/System.out(3303): <head> 04-30 03:15:43.545: INFO/System.out(3303): <title>Busspur online</title> 04-30 03:15:43.554: INFO/System.out(3303): <base href="http://busspur02.aseag.de"> 04-30 03:15:43.554: INFO/System.out(3303): <meta name="description" content="Busspur im Internet"> 04-30 03:15:43.554: INFO/System.out(3303): <meta name="author" content="Dr. Manfred Enning"> 04-30 03:15:43.554: INFO/System.out(3303): <meta name="AUTH_TYPE" content="Basic"> 04-30 03:15:43.574: INFO/System.out(3303): <meta HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=windows-1252"> 04-30 03:15:43.574: INFO/System.out(3303): <meta HTTP-EQUIV="Content-Language" CONTENT="de"> 04-30 03:15:43.574: INFO/System.out(3303): <link rel=stylesheet type="text/css" href="busspur.css"> 04-30 03:15:43.574: INFO/System.out(3303): </head> 04-30 03:15:43.574: INFO/System.out(3303): 04-30 03:15:43.574: INFO/System.out(3303): <body> 04-30 03:15:43.574: INFO/System.out(3303): <table border="0" cellspacing="0" cellpadding="0" width="100%"> 04-30 03:15:43.574: INFO/System.out(3303): <tr> 04-30 03:15:43.584: INFO/System.out(3303): <td align="left" width="25%"><small>Version: 6.8.1.9s2<br>Datenstand: 13.04.2010 04-30 03:15:43.584: INFO/System.out(3303): 04-30 03:15:43.584: INFO/System.out(3303): <br>12.04.2010 - 12.06.2010 04-30 03:15:43.584: INFO/System.out(3303): <br>1663 04-30 03:15:43.584: INFO/System.out(3303): 3D3B9</small> 04-30 03:15:43.584: INFO/System.out(3303): </td> 04-30 03:15:43.584: INFO/System.out(3303): 04-30 03:15:43.584: INFO/System.out(3303): <td align="center" width="50%"> 04-30 03:15:43.584: INFO/System.out(3303): <a href="/bs.exe/SL?Sprache=Nederlands&amp;SID=3D3B9"><img src="http://www.busspur.de/logos/nederlands.gif" alt="Nederlands" border="0" Width="32" Height="22"></a><a href="/bs.exe/SL?Sprache=English&amp;SID=3D3B9"><img src="http://www.busspur.de/logos/english.gif" alt="English" border="0" Width="32" Height="22"></a><a href="/bs.exe/SL?Sprache=Francais&amp;SID=3D3B9"><img src="http://www.busspur.de/logos/francais.gif" alt="Francais" border="0" Width="32" Height="22"></a> 04-30 03:15:43.584: INFO/System.out(3303): </td> 04-30 03:15:43.584: INFO/System.out(3303): 04-30 03:15:43.594: INFO/System.out(3303): <td align="right" width="25%"> 04-30 03:15:43.594: INFO/System.out(3303): <a href="http://www.avv.de/"><img src="/logos/avvlogo.gif" border="0" alt="AVV"></a> 04-30 03:15:43.594: INFO/System.out(3303): </td> 04-30 03:15:43.594: INFO/System.out(3303): </tr> 04-30 03:15:43.594: INFO/System.out(3303): </table> 04-30 03:15:43.594: INFO/System.out(3303): 04-30 03:15:43.594: INFO/System.out(3303): <!-- Kopfbereich (automatisch erzeugt) --> 04-30 03:15:43.594: INFO/System.out(3303): <div align="center"> 04-30 03:15:43.594: INFO/System.out(3303): 04-30 03:15:43.604: INFO/System.out(3303): <H2>Busspur-Online <i>Verbindungsabfrage</i></H2> 04-30 03:15:43.604: INFO/System.out(3303): </div> 04-30 03:15:43.604: INFO/System.out(3303): <!-- Ende Kopfbereich --> 04-30 03:15:43.604: INFO/System.out(3303): 04-30 03:15:43.604: INFO/System.out(3303): <!-- Ausgabebereich (automatisch erzeugt) --> 04-30 03:15:43.604: INFO/System.out(3303): <div align="center"> 04-30 03:15:43.614: INFO/System.out(3303): <p></p> 04-30 03:15:43.614: INFO/System.out(3303): <p></p> 04-30 03:15:43.614: INFO/System.out(3303): 04-30 03:15:43.614: INFO/System.out(3303): 04-30 03:15:43.624: INFO/System.out(3303): </div> 04-30 03:15:43.624: INFO/System.out(3303): <!-- Ende Ausgabebereich --> 04-30 03:15:43.634: INFO/System.out(3303): 04-30 03:15:43.634: INFO/System.out(3303): <!-- Fussnotenbereich (automatisch erzeugt) --> 04-30 03:15:43.634: INFO/System.out(3303): <div align="left"> 04-30 03:15:43.634: INFO/System.out(3303): 04-30 03:15:43.634: INFO/System.out(3303): 04-30 03:15:43.634: INFO/System.out(3303): </div> 04-30 03:15:43.634: INFO/System.out(3303): <!-- Ende Fussnotenbereich --> 04-30 03:15:43.634: INFO/System.out(3303): 04-30 03:15:43.634: INFO/System.out(3303): <!-- Nachschlageliste (automatisch erzeugt) --> 04-30 03:15:43.634: INFO/System.out(3303): <div align="center"> 04-30 03:15:43.644: INFO/System.out(3303): 04-30 03:15:43.644: INFO/System.out(3303): </div> 04-30 03:15:43.644: INFO/System.out(3303): <!-- Ende Nachschlageliste --> 04-30 03:15:43.644: INFO/System.out(3303): 04-30 03:15:43.644: INFO/System.out(3303): 04-30 03:15:43.644: INFO/System.out(3303): <!-- Eingabeformular --> 04-30 03:15:43.644: INFO/System.out(3303): 04-30 03:15:43.644: INFO/System.out(3303): 04-30 03:15:43.644: INFO/System.out(3303): <!-- Eingabeformular --> 04-30 03:15:43.644: INFO/System.out(3303): <form name="Maske" action="/bs.exe" method="get"> 04-30 03:15:43.644: INFO/System.out(3303): 04-30 03:15:43.644: INFO/System.out(3303): <input type="hidden" name="SID" value="3D3B9"> 04-30 03:15:43.644: INFO/System.out(3303): <input type="hidden" name="ScreenX" value=""> 04-30 03:15:43.654: INFO/System.out(3303): <input type="hidden" name="ScreenY" value=""> 04-30 03:15:43.654: INFO/System.out(3303): <input type="hidden" class="hiddenForm" name="CMD" value="CR" /> 04-30 03:15:43.654: INFO/System.out(3303): 04-30 03:15:43.654: INFO/System.out(3303): 04-30 03:15:43.654: INFO/System.out(3303): <input TYPE="Submit" name="Suchen" value="S" tabindex="20" style="visibility:hidden"> 04-30 03:15:43.654: INFO/System.out(3303): 04-30 03:15:43.654: INFO/System.out(3303): <table align="center" border="0" cellspacing="0" cellpadding="2"> 04-30 03:15:43.654: INFO/System.out(3303): <tr> 04-30 03:15:43.654: INFO/System.out(3303): <td class="Haupt"> 04-30 03:15:43.654: INFO/System.out(3303): 04-30 03:15:43.674: INFO/System.out(3303): <table border="0" cellspacing="0" cellpadding="2"> 04-30 03:15:43.674: INFO/System.out(3303): <!-- 1.Zeile Startauswahl --> 04-30 03:15:43.674: INFO/System.out(3303): <tr> 04-30 03:15:43.674: INFO/System.out(3303): <td rowspan="2" class="Start1"> 04-30 03:15:43.674: INFO/System.out(3303): Start 04-30 03:15:43.685: INFO/System.out(3303): </td> 04-30 03:15:43.685: INFO/System.out(3303): 04-30 03:15:43.685: INFO/System.out(3303): <td class="Start2" height="25"> 04-30 03:15:43.685: INFO/System.out(3303): Stadt/Gemeinde 04-30 03:15:43.685: INFO/System.out(3303): </td> 04-30 03:15:43.685: INFO/System.out(3303): 04-30 03:15:43.685: INFO/System.out(3303): <td class="Start3"> 04-30 03:15:43.685: INFO/System.out(3303): <input type="text" name="GT0" value="" tabindex="1" /> 04-30 03:15:43.704: INFO/System.out(3303): 04-30 03:15:43.704: INFO/System.out(3303): </td> 04-30 03:15:43.704: INFO/System.out(3303): 04-30 03:15:43.704: INFO/System.out(3303): 04-30 03:15:43.704: INFO/System.out(3303): <td rowspan="2" class="Start4"> 04-30 03:15:43.714: INFO/System.out(3303): <input type="submit" name="Map0" value="Karte" tabindex="100" /> 04-30 03:15:43.724: INFO/System.out(3303): 04-30 03:15:43.724: INFO/System.out(3303): </td> 04-30 03:15:43.724: INFO/System.out(3303): 04-30 03:15:43.724: INFO/System.out(3303): 04-30 03:15:43.724: INFO/System.out(3303): </tr> 04-30 03:15:43.724: INFO/System.out(3303): 04-30 03:15:43.724: INFO/System.out(3303): <tr> 04-30 03:15:43.734: INFO/System.out(3303): <td class="Start2" height="25"> 04-30 03:15:43.734: INFO/System.out(3303): <select name="T0" id="efaT0"> 04-30 03:15:43.734: INFO/System.out(3303): <option value="A" >Adresse 04-30 03:15:43.734: INFO/System.out(3303): <option value="H" selected="selected">Haltestelle 04-30 03:15:43.734: INFO/System.out(3303): <option value="Z" >Bes. Ziel 04-30 03:15:43.734: INFO/System.out(3303): </select> 04-30 03:15:43.734: INFO/System.out(3303): 04-30 03:15:43.734: INFO/System.out(3303): </td> 04-30 03:15:43.734: INFO/System.out(3303): 04-30 03:15:43.734: INFO/System.out(3303): <td class="Start3"> 04-30 03:15:43.734: INFO/System.out(3303): <input type="text" name="HT0" value="" tabindex="2" /> 04-30 03:15:43.734: INFO/System.out(3303): 04-30 03:15:43.745: INFO/System.out(3303): </td> 04-30 03:15:43.754: INFO/System.out(3303): 04-30 03:15:43.774: INFO/System.out(3303): </tr> 04-30 03:15:43.784: INFO/System.out(3303): 04-30 03:15:43.784: INFO/System.out(3303): <!-- 2.Zeile Ziel oder ViaAuswahl --> 04-30 03:15:43.784: INFO/System.out(3303): 04-30 03:15:43.805: INFO/System.out(3303): <tr> 04-30 03:15:43.834: INFO/System.out(3303): <td rowspan="2" class="Ziel1"> 04-30 03:15:43.834: INFO/System.out(3303): Ziel 04-30 03:15:43.834: INFO/System.out(3303): </td> 04-30 03:15:43.844: INFO/System.out(3303): 04-30 03:15:43.844: INFO/System.out(3303): <td class="Ziel2" height="25"> 04-30 03:15:43.844: INFO/System.out(3303): Stadt/Gemeinde 04-30 03:15:43.844: INFO/System.out(3303): </td> 04-30 03:15:43.854: INFO/System.out(3303): 04-30 03:15:43.854: INFO/System.out(3303): <td class="Ziel3"> 04-30 03:15:43.854: INFO/System.out(3303): Aachen 04-30 03:15:43.864: INFO/System.out(3303): </td> 04-30 03:15:43.874: INFO/System.out(3303): 04-30 03:15:43.874: INFO/System.out(3303): 04-30 03:15:43.884: INFO/System.out(3303): <td rowspan="2" class="Ziel4"> 04-30 03:15:43.884: INFO/System.out(3303): <input type="submit" name="Map1" value="Karte" tabindex="101" /> 04-30 03:15:43.884: INFO/System.out(3303): 04-30 03:15:43.884: INFO/System.out(3303): </td> 04-30 03:15:43.884: INFO/System.out(3303): 04-30 03:15:43.884: INFO/System.out(3303): 04-30 03:15:43.884: INFO/System.out(3303): </tr> 04-30 03:15:43.884: INFO/System.out(3303): 04-30 03:15:43.884: INFO/System.out(3303): <tr> 04-30 03:15:43.884: INFO/System.out(3303): <td class="Ziel2" height="25"> 04-30 03:15:43.894: INFO/System.out(3303): <small></small> 04-30 03:15:43.894: INFO/System.out(3303): </td> 04-30 03:15:43.894: INFO/System.out(3303): <td class="Ziel3"> 04-30 03:15:43.894: INFO/System.out(3303): Karlsgraben 04-30 03:15:43.904: INFO/System.out(3303): </td> 04-30 03:15:43.904: INFO/System.out(3303): </tr> 04-30 03:15:43.904: INFO/System.out(3303): 04-30 03:15:43.914: INFO/System.out(3303): 04-30 03:15:43.924: INFO/System.out(3303): 04-30 03:15:43.934: INFO/System.out(3303): 04-30 03:15:43.934: INFO/System.out(3303): 04-30 03:15:43.934: INFO/System.out(3303): 04-30 03:15:43.934: INFO/System.out(3303): <!-- 3.Zeile Datum/Zeit/Intervall --> 04-30 03:15:43.934: INFO/System.out(3303): <tr> 04-30 03:15:43.944: INFO/System.out(3303): <td rowspan="3" class="Zeit1"> 04-30 03:15:43.944: INFO/System.out(3303): Zeit 04-30 03:15:43.944: INFO/System.out(3303): </td> 04-30 03:15:43.944: INFO/System.out(3303): <td class="Datum2"> 04-30 03:15:43.944: INFO/System.out(3303): Datum 04-30 03:15:43.944: INFO/System.out(3303): </td> 04-30 03:15:43.944: INFO/System.out(3303): 04-30 03:15:43.944: INFO/System.out(3303): <!-- Für Abfragen ohne Karte alternativ Zeile ohne colspan hinzufügen --> 04-30 03:15:43.954: INFO/System.out(3303): 04-30 03:15:43.964: INFO/System.out(3303): <td class="Datum3" height="25" colspan="2"> 04-30 03:15:43.984: INFO/System.out(3303): <select name="DatumT" tabindex="10" id="efaDatumT"> 04-30 03:15:43.984: INFO/System.out(3303): <option >1</option> 04-30 03:15:43.984: INFO/System.out(3303): <option >2</option> 04-30 03:15:43.984: INFO/System.out(3303): <option >3</option> 04-30 03:15:43.984: INFO/System.out(3303): <option >4</option> 04-30 03:15:43.984: INFO/System.out(3303): <option >5</option> 04-30 03:15:43.984: INFO/System.out(3303): <option >6</option> 04-30 03:15:43.984: INFO/System.out(3303): <option >7</option> 04-30 03:15:43.984: INFO/System.out(3303): <option >8</option> 04-30 03:15:43.994: INFO/System.out(3303): <option >9</option> 04-30 03:15:43.994: INFO/System.out(3303): <option >10</option> 04-30 03:15:43.994: INFO/System.out(3303): <option >11</option> 04-30 03:15:43.994: INFO/System.out(3303): <option >12</option> 04-30 03:15:44.005: INFO/System.out(3303): <option >13</option> 04-30 03:15:44.024: INFO/System.out(3303): <option >14</option> 04-30 03:15:44.034: INFO/System.out(3303): <option >15</option> 04-30 03:15:44.034: INFO/System.out(3303): <option >16</option> 04-30 03:15:44.034: INFO/System.out(3303): <option >17</option> 04-30 03:15:44.034: INFO/System.out(3303): <option >18</option> 04-30 03:15:44.044: INFO/System.out(3303): <option >19</option> 04-30 03:15:44.044: INFO/System.out(3303): <option >20</option> 04-30 03:15:44.044: INFO/System.out(3303): <option >21</option> 04-30 03:15:44.044: INFO/System.out(3303): <option >22</option> 04-30 03:15:44.044: INFO/System.out(3303): <option >23</option> 04-30 03:15:44.044: INFO/System.out(3303): <option >24</option> 04-30 03:15:44.044: INFO/System.out(3303): <option >25</option> 04-30 03:15:44.044: INFO/System.out(3303): <option >26</option> 04-30 03:15:44.044: INFO/System.out(3303): <option >27</option> 04-30 03:15:44.044: INFO/System.out(3303): <option >28</option> 04-30 03:15:44.044: INFO/System.out(3303): <option >29</option> 04-30 03:15:44.044: INFO/System.out(3303): <option selected="selected">30</option> 04-30 03:15:44.044: INFO/System.out(3303): <option >31</option> 04-30 03:15:44.055: INFO/System.out(3303): </select> 04-30 03:15:44.055: INFO/System.out(3303): . 04-30 03:15:44.055: INFO/System.out(3303): <select name="DatumM" tabindex="11" id="efaDatumM"> 04-30 03:15:44.055: INFO/System.out(3303): <option >1</option> 04-30 03:15:44.055: INFO/System.out(3303): <option >2</option> 04-30 03:15:44.055: INFO/System.out(3303): <option >3</option> 04-30 03:15:44.064: INFO/System.out(3303): <option selected="selected">4</option> 04-30 03:15:44.064: INFO/System.out(3303): <option >5</option> 04-30 03:15:44.064: INFO/System.out(3303): <option >6</option> 04-30 03:15:44.064: INFO/System.out(3303): <option >7</option> 04-30 03:15:44.064: INFO/System.out(3303): <option >8</option> 04-30 03:15:44.064: INFO/System.out(3303): <option >9</option> 04-30 03:15:44.064: INFO/System.out(3303): <option >10</option> 04-30 03:15:44.064: INFO/System.out(3303): <option >11</option> 04-30 03:15:44.085: INFO/System.out(3303): <option >12</option> 04-30 03:15:44.085: INFO/System.out(3303): </select> 04-30 03:15:44.085: INFO/System.out(3303): . 04-30 03:15:44.085: INFO/System.out(3303): <select name="DatumJ" tabindex="12" id="efaDatumJ"> 04-30 03:15:44.095: INFO/System.out(3303): <option >2009</option> 04-30 03:15:44.095: INFO/System.out(3303): <option selected="selected">2010</option> 04-30 03:15:44.095: INFO/System.out(3303): <option >2011</option> 04-30 03:15:44.095: INFO/System.out(3303): </select> 04-30 03:15:44.095: INFO/System.out(3303): 04-30 03:15:44.095: INFO/System.out(3303): </td> 04-30 03:15:44.095: INFO/System.out(3303): 04-30 03:15:44.105: INFO/System.out(3303): </tr> 04-30 03:15:44.115: INFO/System.out(3303): 04-30 03:15:44.115: INFO/System.out(3303): <tr> 04-30 03:15:44.115: INFO/System.out(3303): <td class="Uhrzeit2"> 04-30 03:15:44.115: INFO/System.out(3303): <input type="radio" name="AbfAnk" value="Abf" checked />Abfahrten ab<br /> 04-30 03:15:44.115: INFO/System.out(3303): <input type="radio" name="AbfAnk" value="Ank" />Ankünfte bis 04-30 03:15:44.115: INFO/System.out(3303): 04-30 03:15:44.115: INFO/System.out(3303): </td> 04-30 03:15:44.125: INFO/System.out(3303): <td class="Uhrzeit3" height="25"> 04-30 03:15:44.125: INFO/System.out(3303): <select name="ZeitH" tabindex="14" id="efaZeitH"> 04-30 03:15:44.125: INFO/System.out(3303): <option >0</option> 04-30 03:15:44.125: INFO/System.out(3303): <option >1</option> 04-30 03:15:44.125: INFO/System.out(3303): <option >2</option> 04-30 03:15:44.135: INFO/System.out(3303): <option >3</option> 04-30 03:15:44.135: INFO/System.out(3303): <option >4</option> 04-30 03:15:44.135: INFO/System.out(3303): <option >5</option> 04-30 03:15:44.135: INFO/System.out(3303): <option >6</option> 04-30 03:15:44.135: INFO/System.out(3303): <option >7</option> 04-30 03:15:44.135: INFO/System.out(3303): <option >8</option> 04-30 03:15:44.145: INFO/System.out(3303): <option >9</option> 04-30 03:15:44.145: INFO/System.out(3303): <option >10</option> 04-30 03:15:44.145: INFO/System.out(3303): <option >11</option> 04-30 03:15:44.145: INFO/System.out(3303): <option >12</option> 04-30 03:15:44.145: INFO/System.out(3303): <option >13</option> 04-30 03:15:44.145: INFO/System.out(3303): <option >14</option> 04-30 03:15:44.145: INFO/System.out(3303): <option selected="selected">15</option> 04-30 03:15:44.145: INFO/System.out(3303): <option >16</option> 04-30 03:15:44.145: INFO/System.out(3303): <option >17</option> 04-30 03:15:44.145: INFO/System.out(3303): <option >18</option> 04-30 03:15:44.145: INFO/System.out(3303): <option >19</option> 04-30 03:15:44.155: INFO/System.out(3303): <option >20</option> 04-30 03:15:44.155: INFO/System.out(3303): <option >21</option> 04-30 03:15:44.155: INFO/System.out(3303): <option >22</option> 04-30 03:15:44.155: INFO/System.out(3303): <option >23</option> 04-30 03:15:44.155: INFO/System.out(3303): </select> 04-30 03:15:44.155: INFO/System.out(3303): : 04-30 03:15:44.155: INFO/System.out(3303): <select name="ZeitM" tabindex="15" id="efaZeitM"> 04-30 03:15:44.155: INFO/System.out(3303): <option >00</option> 04-30 03:15:44.155: INFO/System.out(3303): <option selected="selected">15</option> 04-30 03:15:44.155: INFO/System.out(3303): <option >30</option> 04-30 03:15:44.155: INFO/System.out(3303): <option >45</option> 04-30 03:15:44.155: INFO/System.out(3303): </select> 04-30 03:15:44.155: INFO/System.out(3303): 04-30 03:15:44.155: INFO/System.out(3303): </td> 04-30 03:15:44.155: INFO/System.out(3303): 04-30 03:15:44.165: INFO/System.out(3303): <td class="Uhrzeit2">&nbsp;</td> 04-30 03:15:44.165: INFO/System.out(3303): 04-30 03:15:44.165: INFO/System.out(3303): </tr> 04-30 03:15:44.165: INFO/System.out(3303): 04-30 03:15:44.165: INFO/System.out(3303): <tr> 04-30 03:15:44.165: INFO/System.out(3303): <td class="Intervall2"> 04-30 03:15:44.165: INFO/System.out(3303): Intervall 04-30 03:15:44.165: INFO/System.out(3303): </td> 04-30 03:15:44.184: INFO/System.out(3303): 04-30 03:15:44.184: INFO/System.out(3303): <td class="Intervall3" height="25"> 04-30 03:15:44.184: INFO/System.out(3303): <select name="Intervall" tabindex="13" id="efaIntervall"> 04-30 03:15:44.184: INFO/System.out(3303): <option value="60" >1 h</option> 04-30 03:15:44.184: INFO/System.out(3303): <option value="120" >2 h</option> 04-30 03:15:44.184: INFO/System.out(3303): <option value="240" >4 h</option> 04-30 03:15:44.184: INFO/System.out(3303): <option value="480" >8 h</option> 04-30 03:15:44.184: INFO/System.out(3303): <option value="1800" >ganzer Tag</option> 04-30 03:15:44.194: INFO/System.out(3303): </select> 04-30 03:15:44.194: INFO/System.out(3303): 04-30 03:15:44.204: INFO/System.out(3303): </td> 04-30 03:15:44.204: INFO/System.out(3303): 04-30 03:15:44.204: INFO/System.out(3303): <td class="Intervall3">&nbsp; 04-30 03:15:44.204: INFO/System.out(3303): 04-30 03:15:44.204: INFO/System.out(3303): </tr> 04-30 03:15:44.204: INFO/System.out(3303): </table> 04-30 03:15:44.204: INFO/System.out(3303): 04-30 03:15:44.204: INFO/System.out(3303): </td> 04-30 03:15:44.204: INFO/System.out(3303): 04-30 03:15:44.204: INFO/System.out(3303): <td class="Schalter" valign="top"> 04-30 03:15:44.204: INFO/System.out(3303): <table class="Schalter"> 04-30 03:15:44.204: INFO/System.out(3303): <!-- Buttons --> 04-30 03:15:44.204: INFO/System.out(3303): <tr> 04-30 03:15:44.204: INFO/System.out(3303): <td class="Schalter" align="center"> 04-30 03:15:44.226: INFO/System.out(3303): <input TYPE="Submit" accesskey="s" class="SuchenBtn" name="Suchen" tabindex="20" VALUE="(S)uchen"> 04-30 03:15:44.226: INFO/System.out(3303): </td> 04-30 03:15:44.226: INFO/System.out(3303): </tr> 04-30 03:15:44.226: INFO/System.out(3303): 04-30 03:15:44.226: INFO/System.out(3303): 04-30 03:15:44.226: INFO/System.out(3303): <tr> 04-30 03:15:44.226: INFO/System.out(3303): <td class="Schalter" align="center"> 04-30 03:15:44.226: INFO/System.out(3303): <input TYPE="Submit" accesskey="o" name="Optionen" tabindex="22" VALUE="(O)ptionen"> 04-30 03:15:44.226: INFO/System.out(3303): </td> 04-30 03:15:44.226: INFO/System.out(3303): </tr> 04-30 03:15:44.226: INFO/System.out(3303): 04-30 03:15:44.226: INFO/System.out(3303): 04-30 03:15:44.226: INFO/System.out(3303): <tr> 04-30 03:15:44.226: INFO/System.out(3303): <td class="Schalter" align="center"> 04-30 03:15:44.226: INFO/System.out(3303): <input TYPE="Button" accesskey="z" tabindex="24" VALUE="(Z)urück" onClick="history.back()"> 04-30 03:15:44.226: INFO/System.out(3303): </td> 04-30 03:15:44.226: INFO/System.out(3303): </tr> 04-30 03:15:44.226: INFO/System.out(3303): <tr> 04-30 03:15:44.226: INFO/System.out(3303): <td class="Schalter" align="center"> 04-30 03:15:44.226: INFO/System.out(3303): <input TYPE="Button" accesskey="h" tabindex="25" VALUE="(H)ilfe" onClick="self.location.href='/bs.exe/FF?N=hilfe&amp;SID=3D3B9'"> 04-30 03:15:44.226: INFO/System.out(3303): </td> 04-30 03:15:44.235: INFO/System.out(3303): </tr> 04-30 03:15:44.235: INFO/System.out(3303): <tr> 04-30 03:15:44.235: INFO/System.out(3303): <td class="Schalter" align="center"> 04-30 03:15:44.235: INFO/System.out(3303): <input TYPE="Submit" accesskey="n" tabindex="26" name="Loeschen" VALUE="(N)eue Suche"> 04-30 03:15:44.235: INFO/System.out(3303): </td> 04-30 03:15:44.235: INFO/System.out(3303): </tr> 04-30 03:15:44.235: INFO/System.out(3303): 04-30 03:15:44.235: INFO/System.out(3303): <tr> 04-30 03:15:44.235: INFO/System.out(3303): 04-30 03:15:44.244: INFO/System.out(3303): <td class="Schalter" align="center"> 04-30 03:15:44.244: INFO/System.out(3303): <input TYPE="Button" accesskey="a" tabindex="27" VALUE="H(a)ltestelle" onClick="self.location.href='/bs.exe/RHFF?Karten=true?N=Result&amp;SID=3D3B9'"> 04-30 03:15:44.244: INFO/System.out(3303): </td> 04-30 03:15:44.244: INFO/System.out(3303): 04-30 03:15:44.244: INFO/System.out(3303): </tr> 04-30 03:15:44.244: INFO/System.out(3303): </table> 04-30 03:15:44.254: INFO/System.out(3303): 04-30 03:15:44.254: INFO/System.out(3303): </td> 04-30 03:15:44.254: INFO/System.out(3303): </tr> 04-30 03:15:44.254: INFO/System.out(3303): </table> 04-30 03:15:44.254: INFO/System.out(3303): </form> 04-30 03:15:44.254: INFO/System.out(3303): 04-30 03:15:44.254: INFO/System.out(3303): 04-30 03:15:44.254: INFO/System.out(3303): <!-- Meldungsbereich (automatisch erzeugt) --> 04-30 03:15:44.254: INFO/System.out(3303): <div align="center" id="meldungen"> 04-30 03:15:44.265: INFO/System.out(3303): <table class="Bedienhinweise"><tr><td rowspan="2"><img SRC="http://www.busspur.de/logos/hinweis.png" ALIGN="top" alt="Symbol" WIDTH="32" HEIGHT="20">&nbsp;</td><td rowspan="2">Start</td><td>Geben Sie den Namen der Stadt/Gemeinde ein</td></tr><tr><td>Geben Sie den Namen der Haltestelle ein</td></tr></table> 04-30 03:15:44.265: INFO/System.out(3303): </div> 04-30 03:15:44.265:

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• Design for a plugin based application

  - by Varun Naik

  I am working on application, details of which I cannot discuss here. We have core framework and the rest is designed as plug in. In the core framework we have a domain object. This domain object is updated by the plugins. I have defined an interface in which I have function as DomainObject doProcessing(DomainObject object) My intention here is I pass the domain object, the plug in will update it and return it. This updated object is then passed again to different plugin to be updated. I am not sure if this is a good approach. I don't like passing the DomainObject to plugin. Is there a better way I can achieve this? Should I just request data from plugin and update the domain object myself?

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• Single database, multiple system dependency

  - by davenewza

  Consider an environment where we have a single, core database, with many separate systems using this one database. This leads to all of these systems have a common dependency, which ultimately introduces coupling between them. This means that we cannot always evolve systems independently of each other. Structural changes to the database (even if only intended for one, particular system), requires a full sweep test of ALL systems, and may require that other systems be 'patched' and subsequently released. This is especially tricky when you want to have separate teams working on different projects. What is a good 'pattern' to help in avoiding such coupling? I would imagine that a database should be exclusively depended on by one system. If other systems require data for whatever reason, they should request such from an API service of some kind. A drawback of this approach which comes to mind is performance: routing data between high-throughput systems through service calls is much slower than through a database connection.

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• Class Design and Structure Online Web Store

  - by Phorce

  I hope I have asked this in the right forum. Basically, we're designing an Online Store and I am designing the class structure for ordering a product and want some clarification on what I have so far: So a customer comes, selects their product, chooses the quantity and selects 'Purchase' (I am using the Facade Pattern - So subsystems execute when this action is performed). My class structure: < Order > < Product > <Customer > There is no inheritance, more Association < Order has < Product , < Customer has < Order . Does this structure look ok? I've noticed that I don't handle the "Quantity" separately, I was just going to add this into the "Product" class, but, do you think it should be a class of it's own? Hope someone can help.

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• Caching factory design

  - by max

  I have a factory class XFactory that creates objects of class X. Instances of X are very large, so the main purpose of the factory is to cache them, as transparently to the client code as possible. Objects of class X are immutable, so the following code seems reasonable: # module xfactory.py import x class XFactory: _registry = {} def get_x(self, arg1, arg2, use_cache = True): if use_cache: hash_id = hash((arg1, arg2)) if hash_id in _registry: return _registry[hash_id] obj = x.X(arg1, arg2) _registry[hash_id] = obj return obj # module x.py class X: # ... Is it a good pattern? (I know it's not the actual Factory Pattern.) Is there anything I should change? Now, I find that sometimes I want to cache X objects to disk. I'll use pickle for that purpose, and store as values in the _registry the filenames of the pickled objects instead of references to the objects. Of course, _registry itself would have to be stored persistently (perhaps in a pickle file of its own, in a text file, in a database, or simply by giving pickle files the filenames that contain hash_id). Except now the validity of the cached object depends not only on the parameters passed to get_x(), but also on the version of the code that created these objects. Strictly speaking, even a memory-cached object could become invalid if someone modifies x.py or any of its dependencies, and reloads it while the program is running. So far I ignored this danger since it seems unlikely for my application. But I certainly cannot ignore it when my objects are cached to persistent storage. What can I do? I suppose I could make the hash_id more robust by calculating hash of a tuple that contains arguments arg1 and arg2, as well as the filename and last modified date for x.py and every module and data file that it (recursively) depends on. To help delete cache files that won't ever be useful again, I'd add to the _registry the unhashed representation of the modified dates for each record. But even this solution isn't 100% safe since theoretically someone might load a module dynamically, and I wouldn't know about it from statically analyzing the source code. If I go all out and assume every file in the project is a dependency, the mechanism will still break if some module grabs data from an external website, etc.). In addition, the frequency of changes in x.py and its dependencies is quite high, leading to heavy cache invalidation. Thus, I figured I might as well give up some safety, and only invalidate the cache only when there is an obvious mismatch. This means that class X would have a class-level cache validation identifier that should be changed whenever the developer believes a change happened that should invalidate the cache. (With multiple developers, a separate invalidation identifier is required for each.) This identifier is hashed along with arg1 and arg2 and becomes part of the hash keys stored in _registry. Since developers may forget to update the validation identifier or not realize that they invalidated existing cache, it would seem better to add another validation mechanism: class X can have a method that returns all the known "traits" of X. For instance, if X is a table, I might add the names of all the columns. The hash calculation will include the traits as well. I can write this code, but I am afraid that I'm missing something important; and I'm also wondering if perhaps there's a framework or package that can do all of this stuff already. Ideally, I'd like to combine in-memory and disk-based caching.

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• Design for object with optional and modifiable attributtes?

  - by Ikuzen

  I've been using the Builder pattern to create objects with a large number of attributes, where most of them are optional. But up until now, I've defined them as final, as recommended by Joshua Block and other authors, and haven't needed to change their values. I am wondering what should I do though if I need a class with a substantial number of optional but non-final (mutable) attributes? My Builder pattern code looks like this: public class Example { //All possible parameters (optional or not) private final int param1; private final int param2; //Builder class public static class Builder { private final int param1; //Required parameters private int param2 = 0; //Optional parameters - initialized to default //Builder constructor public Builder (int param1) { this.param1 = param1; } //Setter-like methods for optional parameters public Builder param2(int value) { param2 = value; return this; } //build() method public Example build() { return new Example(this); } } //Private constructor private Example(Builder builder) { param1 = builder.param1; param2 = builder.param2; } } Can I just remove the final keyword from the declaration to be able to access the attributes externally (through normal setters, for example)? Or is there a creational pattern that allows optional but non-final attributes that would be better suited in this case?

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• Learning how to design knowledge and data flow [closed]

  - by max

  In designing software, I spend a lot of time deciding how the knowledge (algorithms / business logic) and data should be allocated between different entities; that is, which object should know what. I am asking for advice about books, articles, presentations, classes, or other resources that would help me learn how to do it better. I code primarily in Python, but my question is not really language-specific; even if some of the insights I learn don't work in Python, that's fine. I'll give a couple examples to clarify what I mean. Example 1 I want to perform some computation. As a user, I will need to provide parameters to do the computation. I can have all those parameters sent to the "main" object, which then uses them to create other objects as needed. Or I can create one "main" object, as well as several additional objects; the additional objects would then be sent to the "main" object as parameters. What factors should I consider to make this choice? Example 2 Let's say I have a few objects of type A that can perform a certain computation. The main computation often involves using an object of type B that performs some interim computation. I can either "teach" A instances what exact parameters to pass to B instances (i.e., make B "dumb"); or I can "teach" B instances to figure out what needs to be done when looking at an A instance (i.e., make B "smart"). What should I think about when I'm making this choice?

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• High-Level Application Architecture Question

  - by Jesse Bunch

  So I'm really wanting to improve how I architect the software I code. I want to focus on maintainability and clean code. As you might guess, I've been reading a lot of resources on this topic and all it's doing is making it harder for me to settle on an architecture because I can never tell if my design is the one that the more experienced programmer would've chosen. So I have these requirements: I should connect to one vendor and download form submissions from their API. We'll call them the CompanyA. I should then map those submissions to a schema fit for submitting to another vendor for integration with the email service provider. We'll call them the CompanyB. I should then submit those responses to the ESP (CompanyB) and then instruct the ESP to send that submitter an email. So basically, I'm copying data from one web service to another and then performing an action at the latter web service. I've identified a couple high-level services: The service that downloads data from CompanyA. I called this the CompanyAIntegrator. The service that submits the data to CompanyB. I called this CompanyBIntegrator. So my questions are these: Is this a good design? I've tried to separate the concerns and am planning to use the facade pattern to make the integrators interchangeable if the vendors change in the future. Are my naming conventions accurate and meaningful to you (who knows nothing specific of the project)? Now that I have these services, where should I do the work of taking output from the CompanyAIntegrator and getting it in the format for input to the CompanyBIntegrator? Is this OK to be done in main()? Do you have any general pointers on how you'd code something like this? I imagine this scenario is common to us engineers---especially those working in agencies. Thanks for any help you can give. Learning how to architect well is really mind-cluttering.

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• How bad is it to have two methods with the same name but different signatures in two classes?

  - by Super User

  I have a design problem related to a public interface, the names of methods, and the understanding of my API and code. I have two classes like this: class A: ... function collision(self): .... ... class B: .... function _collision(self, another_object, l, r, t, b): .... The first class has one public method named collision, and the second has one private method called _collision. The two methods differs in argument type and number. As an example let's say that _collision checks if the object is colliding with another object with certain conditions l, r, t, b (collide on the left side, right side, etc) and returns true or false. The public collision method, on the other hand, resolves all the collisions of the object with other objects. The two methods have the same name because I think it's better to avoid overloading the design with different names for methods that do almost the same thing, but in distinct contexts and classes. Is this clear enough to the reader or I should change the method's name?

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• How bad it's have two methods with the same name but differents signatures in two classes?

  - by Super User

  I have a design problem relationated with the public interface, the names of methods and the understanding of my API and my code. I have two classes like this: class A: ... function collision(self): .... ... class B: .... function _collision(self, another_object, l, r, t, b): .... The first class have one public method named collision and the second have one private method called _collision. The two methods differs in arguments type and number. In the API _m method is private. For the example let's say that the _collision method checks if the object is colliding with another_ object with certain conditions l, r, t, b (for example, collide the left side, the right side, etc) and returns true or false according to the case. The collision method, on the other hand, resolves all the collisions of the object with other objects. The two methods have the same name because I think is better avoid overload the design with different names for methods who do almost the same think, but in distinct contexts and classes. This is clear enough to the reader or I should change the method's name?

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• Templates for forms, tabs etc? - Patterntap alternatives

  - by Marco Demaio

  I used to find http://www.patterntap.com quite useful to get design inspiration for forms, tabs, and other web elements etc. Unfortunately after the ZURB acquisition of Patterntap now they enforce you to sign in with your Twitter account in order to simply view larger images of patterns provided by the crowd. So in some way it's not free anymore. Do you know of alternatives to patterntap that are free and you are not obliged to sign in?

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• Representing complex object dependencies

  - by max

  I have several classes with a reasonably complex (but acyclic) dependency graph. All the dependencies are of the form: class X instance contains an attribute of class Y. All such attributes are set during initialization and never changed again. Each class' constructor has just a couple parameters, and each object knows the proper parameters to pass to the constructors of the objects it contains. class Outer is at the top of the dependency hierarchy, i.e., no class depends on it. Currently, the UI layer only creates an Outer instance; the parameters for Outer constructor are derived from the user input. Of course, Outer in the process of initialization, creates the objects it needs, which in turn create the objects they need, and so on. The new development is that the a user who knows the dependency graph may want to reach deep into it, and set the values of some of the arguments passed to constructors of the inner classes (essentially overriding the values used currently). How should I change the design to support this? I could keep the current approach where all the inner classes are created by the classes that need them. In this case, the information about "user overrides" would need to be passed to Outer class' constructor in some complex user_overrides structure. Perhaps user_overrides could be the full logical representation of the dependency graph, with the overrides attached to the appropriate edges. Outer class would pass user_overrides to every object it creates, and they would do the same. Each object, before initializing lower level objects, will find its location in that graph and check if the user requested an override to any of the constructor arguments. Alternatively, I could rewrite all the objects' constructors to take as parameters the full objects they require. Thus, the creation of all the inner objects would be moved outside the whole hierarchy, into a new controller layer that lies between Outer and UI layer. The controller layer would essentially traverse the dependency graph from the bottom, creating all the objects as it goes. The controller layer would have to ask the higher-level objects for parameter values for the lower-level objects whenever the relevant parameter isn't provided by the user. Neither approach looks terribly simple. Is there any other approach? Has this problem come up enough in the past to have a pattern that I can read about? I'm using Python, but I don't think it matters much at the design level.

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• In database table design, how does "Virtual Goods" affect table design -- should we create an instan

  - by Jian Lin

  When we design a database table for a DVD rental company, we actually have a movie, which is an abstract idea, and a physical DVD, so for each rental, we have a many-to-many table with fields such as: TransactionID UserID DvdID RentedDate RentalDuration AmountPaid but what about with virtual goods? For example, if we let a user rent a movie online for 3 days, we don't actually have a DVD, so we may have a table: TransactionID UserID MovieID RentedDate RentalDuration AmountPaid should we create a record for each instance of "virtual good"? For example, what if this virtual good (the movie) can be authorized to be watched on 3 devices (with 3 device IDs), then should we then create a virtual good record in the VirtualGoods table, each with a VirtualGoodID and then another table that has VirtualGoodID DeviceID to match up the movie with the DeviceIDs? We can also just use the TransactionID as the VirtualGoodID. Are there circumstances where we may want to create a record to record this "virtual good" in a VirtualGoods table?

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• StackOverflowException throws often when .net application built with Debug mode

  - by user1487950

  I have an application which access an external webservice often, when i are trying to debug it, means debuging in vistual studio. it often throws out StackOverflowException at the webserverice call point. when building in Release mode , the exception thrown out only occasionally. I checked the call stack, looks like there is no recursive call. can you please suggest? thank you very much. call statck attached. [In a sleep, wait, or join] mscorlib.dll!System.Threading.WaitHandle.InternalWaitOne(System.Runtime.InteropServices.SafeHandle waitableSafeHandle, long millisecondsTimeout, bool hasThreadAffinity, bool exitContext) + 0x2b bytes mscorlib.dll!System.Threading.WaitHandle.WaitOne(int millisecondsTimeout, bool exitContext) + 0x2d bytes System.dll!System.Net.NetworkAddressChangePolled.CheckAndReset() + 0x9d bytes System.dll!System.Net.NclUtilities.LocalAddresses.get() + 0x49 bytes System.dll!System.Net.WebProxyScriptHelper.myIpAddress() + 0x27 bytes [Native to Managed Transition] System.dll!System.Net.WebProxyScriptHelper.MyMethodInfo.Invoke(object target, System.Reflection.BindingFlags bindingAttr, System.Reflection.Binder binder, object[] args, System.Globalization.CultureInfo culture) + 0x6b bytes MTOqoHCT.dll!JScript 0.myIpAddress(object this, Microsoft.JScript.Vsa.VsaEngine vsa Engine, object arguments) + 0x91 bytes MTOqoHCT.dll!JScript 0.FindProxyForURL(object this, Microsoft.JScript.Vsa.VsaEngine vsa Engine, object arguments, object url, object host) + 0x3c6e bytes MTOqoHCT.dll!__WebProxyScript.__WebProxyScript.ExecuteFindProxyForURL(object url, object host) + 0x11d bytes [Native to Managed Transition] Microsoft.JScript.dll!System.Net.VsaWebProxyScript.CallMethod(object targetObject, string name, object[] args) + 0x11a bytes Microsoft.JScript.dll!System.Net.VsaWebProxyScript.Run(string url, string host) + 0x74 bytes [Native to Managed Transition] [Managed to Native Transition] mscorlib.dll!System.Runtime.Remoting.Messaging.StackBuilderSink.SyncProcessMessage(System.Runtime.Remoting.Messaging.IMessage msg, int methodPtr, bool fExecuteInContext) + 0x1ef bytes mscorlib.dll!System.Runtime.Remoting.Messaging.StackBuilderSink.SyncProcessMessage(System.Runtime.Remoting.Messaging.IMessage msg) + 0xf bytes mscorlib.dll!System.Runtime.Remoting.Messaging.ServerObjectTerminatorSink.SyncProcessMessage(System.Runtime.Remoting.Messaging.IMessage reqMsg) + 0x66 bytes mscorlib.dll!System.Runtime.Remoting.Messaging.ServerContextTerminatorSink.SyncProcessMessage(System.Runtime.Remoting.Messaging.IMessage reqMsg) + 0x8a bytes mscorlib.dll!System.Runtime.Remoting.Channels.CrossContextChannel.SyncProcessMessageCallback(object[] args) + 0x94 bytes mscorlib.dll!System.Threading.Thread.CompleteCrossContextCallback(System.Threading.InternalCrossContextDelegate ftnToCall, object[] args) + 0x8 bytes [Native to Managed Transition] [Managed to Native Transition] mscorlib.dll!System.Runtime.Remoting.Channels.CrossContextChannel.SyncProcessMessage(System.Runtime.Remoting.Messaging.IMessage reqMsg) + 0xa7 bytes mscorlib.dll!System.Runtime.Remoting.Channels.ChannelServices.SyncDispatchMessage(System.Runtime.Remoting.Messaging.IMessage msg) + 0x92 bytes mscorlib.dll!System.Runtime.Remoting.Channels.CrossAppDomainSink.DoDispatch(byte[] reqStmBuff, System.Runtime.Remoting.Messaging.SmuggledMethodCallMessage smuggledMcm, out System.Runtime.Remoting.Messaging.SmuggledMethodReturnMessage smuggledMrm) + 0xed bytes mscorlib.dll!System.Runtime.Remoting.Channels.CrossAppDomainSink.DoTransitionDispatchCallback(object[] args) + 0x8a bytes mscorlib.dll!System.Threading.Thread.CompleteCrossContextCallback(System.Threading.InternalCrossContextDelegate ftnToCall, object[] args) + 0x8 bytes [Appdomain Transition] mscorlib.dll!System.Runtime.Remoting.Channels.CrossAppDomainSink.DoTransitionDispatch(byte[] reqStmBuff, System.Runtime.Remoting.Messaging.SmuggledMethodCallMessage smuggledMcm, out System.Runtime.Remoting.Messaging.SmuggledMethodReturnMessage smuggledMrm) + 0x74 bytes mscorlib.dll!System.Runtime.Remoting.Channels.CrossAppDomainSink.SyncProcessMessage(System.Runtime.Remoting.Messaging.IMessage reqMsg) + 0xa3 bytes mscorlib.dll!System.Runtime.Remoting.Proxies.RemotingProxy.CallProcessMessage(System.Runtime.Remoting.Messaging.IMessageSink ms, System.Runtime.Remoting.Messaging.IMessage reqMsg, System.Runtime.Remoting.Contexts.ArrayWithSize proxySinks, System.Threading.Thread currentThread, System.Runtime.Remoting.Contexts.Context currentContext, bool bSkippingContextChain) + 0x50 bytes mscorlib.dll!System.Runtime.Remoting.Proxies.RemotingProxy.InternalInvoke(System.Runtime.Remoting.Messaging.IMethodCallMessage reqMcmMsg, bool useDispatchMessage, int callType) + 0x1d5 bytes mscorlib.dll!System.Runtime.Remoting.Proxies.RemotingProxy.Invoke(System.Runtime.Remoting.Messaging.IMessage reqMsg) + 0x66 bytes mscorlib.dll!System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(ref System.Runtime.Remoting.Proxies.MessageData msgData, int type) + 0xee bytes System.dll!System.Net.NetWebProxyFinder.GetProxies(System.Uri destination, out System.Collections.Generic.IList<string> proxyList) + 0x83 bytes System.dll!System.Net.AutoWebProxyScriptEngine.GetProxies(System.Uri destination, out System.Collections.Generic.IList<string> proxyList, ref int syncStatus) + 0x84 bytes System.dll!System.Net.WebProxy.GetProxiesAuto(System.Uri destination, ref int syncStatus) + 0x2e bytes System.dll!System.Net.ProxyScriptChain.GetNextProxy(out System.Uri proxy) + 0x2e bytes System.dll!System.Net.ProxyChain.ProxyEnumerator.MoveNext() + 0x98 bytes System.dll!System.Net.ServicePointManager.FindServicePoint(System.Uri address, System.Net.IWebProxy proxy, out System.Net.ProxyChain chain, ref System.Net.HttpAbortDelegate abortDelegate, ref int abortState) + 0x120 bytes System.dll!System.Net.HttpWebRequest.FindServicePoint(bool forceFind) + 0xb1 bytes System.dll!System.Net.HttpWebRequest.GetRequestStream(out System.Net.TransportContext context) + 0x247 bytes System.dll!System.Net.HttpWebRequest.GetRequestStream() + 0xe bytes System.Web.Services.dll!System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(string methodName, object[] parameters) + 0xc0 bytes Gfinet.Config.dll!Gfinet.Config.Service.cfg_webservice.addOrUpdateProperties(string string, int intVal, Gfinet.Config.Service.PropertiesDataM[] propertiesDataMs) + 0xa3 bytes Gfinet.Config.dll!Gfinet.Config.Service.WSServiceImpl.AddOrUpdateProperties(int setId, Gfinet.Config.Service.PropertiesDataM[] properties) + 0x46 bytes [Native to Managed Transition] Gfinet.Config.dll!Gfinet.Config.Service.ServiceAspect.InvocationHandler(object target, System.Reflection.MethodBase method, object[] parameters) + 0x49e bytes Gfinet.Config.dll!Gfinet.Config.DynamicProxy.DynamicProxyImpl.Invoke(System.Runtime.Remoting.Messaging.IMessage message) + 0x110 bytes mscorlib.dll!System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(ref System.Runtime.Remoting.Proxies.MessageData msgData, int type) + 0xee bytes Tici.Kraps.Services.dll!Tici.Kraps.Services.Configuration.GFINetConfiguration.StoreElement(string application, string category, string id, string elementValue, bool save) Line 303 + 0x55 bytes C# Tici.Kraps.Services.dll!Tici.Kraps.Services.Configuration.GFINetConfiguration.SaveAllInternal() Line 582 + 0x6e bytes C# Tici.Kraps.Services.dll!Tici.Kraps.Services.Configuration.GFINetConfiguration.SaveAll(bool async) Line 434 + 0x8 bytes C# Tici.Kraps.Services.dll!Tici.Kraps.Services.Configuration.GFINetConfiguration.SaveAll() Line 406 + 0xa bytes C# Tici.Kraps.Services.dll!Tici.Kraps.Services.Container.Persistor.Save() Line 59 + 0xc bytes C# Spark.exe!Tici.Kraps.RibbonShell.OnBtnSaveWorkspaceItemClick(object sender, DevExpress.XtraBars.ItemClickEventArgs e) Line 642 + 0xf bytes C# DevExpress.XtraBars.v11.2.dll!DevExpress.XtraBars.BarItem.OnClick(DevExpress.XtraBars.BarItemLink link) + 0x108 bytes DevExpress.XtraBars.v11.2.dll!DevExpress.XtraBars.BarBaseButtonItem.OnClick(DevExpress.XtraBars.BarItemLink link) + 0x47 bytes DevExpress.XtraBars.v11.2.dll!DevExpress.XtraBars.BarItemLink.OnLinkClick() + 0x245 bytes DevExpress.XtraBars.v11.2.dll!DevExpress.XtraBars.BarItemLink.OnLinkAction(DevExpress.XtraBars.BarLinkAction action, object actionArgs) + 0xb3 bytes DevExpress.XtraBars.v11.2.dll!DevExpress.XtraBars.BarButtonItemLink.OnLinkAction(DevExpress.XtraBars.BarLinkAction action, object actionArgs) + 0x47e bytes DevExpress.XtraBars.v11.2.dll!DevExpress.XtraBars.BarItemLink.OnLinkActionCore(DevExpress.XtraBars.BarLinkAction action, object actionArgs) + 0x82 bytes DevExpress.XtraBars.v11.2.dll!DevExpress.XtraBars.ViewInfo.BarSelectionInfo.ClickLink(DevExpress.XtraBars.BarItemLink link) + 0x85 bytes DevExpress.XtraBars.v11.2.dll!DevExpress.XtraBars.ViewInfo.BarSelectionInfo.UnPressLink(DevExpress.XtraBars.BarItemLink link) + 0x1e5 bytes DevExpress.XtraBars.v11.2.dll!DevExpress.XtraBars.Ribbon.Handler.BaseRibbonHandler.OnUnPressItem(DevExpress.Utils.DXMouseEventArgs e, DevExpress.XtraBars.Ribbon.ViewInfo.RibbonHitInfo hitInfo) + 0xa7 bytes DevExpress.XtraBars.v11.2.dll!DevExpress.XtraBars.Ribbon.Handler.BaseRibbonHandler.OnUnPress(DevExpress.Utils.DXMouseEventArgs e, DevExpress.XtraBars.Ribbon.ViewInfo.RibbonHitInfo hitInfo) + 0x5f bytes DevExpress.XtraBars.v11.2.dll!DevExpress.XtraBars.Ribbon.Handler.BaseRibbonHandler.OnMouseUp(DevExpress.Utils.DXMouseEventArgs e) + 0x19a bytes DevExpress.XtraBars.v11.2.dll!DevExpress.XtraBars.Ribbon.Handler.RibbonHandler.OnMouseUp(DevExpress.Utils.DXMouseEventArgs e) + 0x47 bytes DevExpress.XtraBars.v11.2.dll!DevExpress.XtraBars.Ribbon.RibbonControl.OnMouseUp(System.Windows.Forms.MouseEventArgs e) + 0x95 bytes System.Windows.Forms.dll!System.Windows.Forms.Control.WmMouseUp(ref System.Windows.Forms.Message m, System.Windows.Forms.MouseButtons button, int clicks) + 0x2d1 bytes System.Windows.Forms.dll!System.Windows.Forms.Control.WndProc(ref System.Windows.Forms.Message m) + 0x93a bytes DevExpress.Utils.v11.2.dll!DevExpress.Utils.Controls.ControlBase.WndProc(ref System.Windows.Forms.Message m) + 0x81 bytes DevExpress.XtraBars.v11.2.dll!DevExpress.XtraBars.Ribbon.RibbonControl.WndProc(ref System.Windows.Forms.Message m) + 0x85 bytes System.Windows.Forms.dll!System.Windows.Forms.Control.ControlNativeWindow.OnMessage(ref System.Windows.Forms.Message m) + 0x13 bytes System.Windows.Forms.dll!System.Windows.Forms.Control.ControlNativeWindow.WndProc(ref System.Windows.Forms.Message m) + 0x31 bytes System.Windows.Forms.dll!System.Windows.Forms.NativeWindow.Callback(System.IntPtr hWnd, int msg, System.IntPtr wparam, System.IntPtr lparam) + 0x96 bytes [Native to Managed Transition] [Managed to Native Transition] DevExpress.Utils.v11.2.dll!DevExpress.Utils.Win.Hook.ControlWndHook.WindowProc(System.IntPtr hWnd, int message, System.IntPtr wParam, System.IntPtr lParam) + 0x159 bytes [Native to Managed Transition] [Managed to Native Transition] System.Windows.Forms.dll!System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(System.IntPtr dwComponentID, int reason, int pvLoopData) + 0x287 bytes System.Windows.Forms.dll!System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(int reason, System.Windows.Forms.ApplicationContext context) + 0x16c bytes System.Windows.Forms.dll!System.Windows.Forms.Application.ThreadContext.RunMessageLoop(int reason, System.Windows.Forms.ApplicationContext context) + 0x61 bytes System.Windows.Forms.dll!System.Windows.Forms.Application.Run(System.Windows.Forms.Form mainForm) + 0x31 bytes Tici.Kraps.Services.dll!Tici.Kraps.Services.Container.DefaultApplicationRunner.Run() Line 41 + 0x17 bytes C# Kraps.exe!Tici.Kraps.Program.Main() Line 105 + 0x9 bytes C# [Native to Managed Transition] [Managed to Native Transition] mscorlib.dll!System.AppDomain.ExecuteAssembly(string assemblyFile, System.Security.Policy.Evidence assemblySecurity, string[] args) + 0x6d bytes Microsoft.VisualStudio.HostingProcess.Utilities.dll!Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly() + 0x2a bytes mscorlib.dll!System.Threading.ThreadHelper.ThreadStart_Context(object state) + 0x63 bytes mscorlib.dll!System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state, bool ignoreSyncCtx) + 0xb0 bytes mscorlib.dll!System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state) + 0x2c bytes mscorlib.dll!System.Threading.ThreadHelper.ThreadStart() + 0x44 bytes [Native to Managed Transition]

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• What do you do if you reach a design dead-end in evolutionary methods like Agile or XP?

  - by Dipan Mehta

  As I was reading Martin Fowler's famous blog post Is Design Dead?, one of the striking impressions I got is that given the fact that in Agile Methodology and Extreme Programming, the design as well as programming is evolutionary, there are always points where things need to get refactored. It may be possible that when a programmer's level is good, and they understand design implications and don't make critical mistakes, the code continues to evolve. However, in a normal context, what is the ground reality in this context? In a normal day given some significant development goes into product, and when critical change occurs in requirement isn't it a constraint that how much ever we wish, fundamental design aspects cannot be modified? (without throwing away major part of the code). Is it not quite likely that one reaches dead-end on any further possible improvement on design and requirements? I am not advocating any non-Agile practice here, but I want to know from people who practice agile or iterative or evolutionary development methods, as for their real experiences. Have you ever reached such dead-ends? How have you managed to avoid it or escaped it? Or are there measures to ensure that design remains clean and flexible as it evolves?

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• Functional/nonfunctional requirements VS design ideas

  - by Nicholas Chow

  Problem domain Functional requirements defines what a system does. Non-Functional requirements defines quality attributes of what the system does as a whole.(performance, security, reliability, volume, useability, etc.) Constraints limits the design space, they restrict designers to certain types of solutions. Solution domain Design ideas , defines how the system does it. For example a stakeholder need might be we want to increase our sales, therefore we must improve the usability of our webshop so more customers will purchase, a requirement can be written for this. (problem domain) Design takes this further into the solution domain by saying "therefore we want to offer credit card payments in addition to the current prepayment option". My problem is that the transition phase from requirement to design seems really vague, therefore when writing requirements I am often confused whether or not I incorporated design ideas in my requirements, that would make my requirement wrong. Another problem is that I often write functional requirements as what a system does, and then I also specify in what timeframe it must be done. But is this correct? Is it then a still a functional requirement or a non functional one? Is it better to seperate it into two distinct requirements? Here are a few requirements I wrote: FR1 Registration of Organizer FR1 describes the registration of an Organizer on CrowdFundum FR1.1 The system shall display a registration form on the website. FR1.2 The system shall require a Name, Username, Document number passport/ID card, Address, Zip code, City, Email address, Telephone number, Bank account, Captcha code on the registration form when a user registers. FR1.4 The system shall display an error message containing: “Registration could not be completed” to the subscriber within 1 seconds after the system check of the registration form was unsuccessful. FR1.5 The system shall send a verification email containing a verification link to the subscriber within 30 seconds after the system check of the registration form was successful. FR1.6 The system shall add the newly registered Organizer to the user base within 5 seconds after the verification link was accessed. FR2 Organizer submits a Project FR2 describes the submission of a Project by an Organizer on CrowdFundum - FR2 The system shall display a submit Project form to the Organizer accounts on the website.< - FR2.3 The system shall check for completeness the Name of the Project, 1-3 Photo’s, Keywords of the Project, Punch line, Minimum and maximum amount of people, Funding threshold, One or more reward tiers, Schedule of when what will be organized, Budget plan, 300-800 Words of additional information about the Project, Contact details within 1 secondin after an Organizer submits the submit Project form. - FR2.8 The system shall add to the homepage in the new Projects category the Project link within 30 seconds after the system made a Project webpage - FR2.9 The system shall include in the Project link for the homepage : Name of the Project, 1 Photo, Punch line within 30 seconds after the system made a Project webpage. Questions: FR 1.1 : Have I incorporated a design idea here, would " the system shall have a registration form" be a better functional requirement? F1.2 ,2.3 : Is this not singular? Would the conditions be better written for each its own separate requirement FR 1.4: Is this a design idea? Is this a correct functional requirement or have I incorporated non functional(performance) in it? Would it be better if I written it like this: FR1 The system shall display an error message when check is unsuccessful. NFR: The system will respond to unsuccesful registration form checks within 1 seconds. Same question with FR 2.8 and 2.9. FR2.3: The system shall check for "completeness", is completeness here used ambigiously? Should I rephrase it? FR1.2: I added that the system shall require a "Captcha code" is this a functional requirement or does it belong to the "security aspect" of a non functional requirement. I am eagerly waiting for your response. Thanks!

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• Question on the implementation of my Entity System

  - by miguel.martin

  I am currently creating an Entity System, in C++, it is almost completed (I have all the code there, I just have to add a few things and test it). The only thing is, I can't figure out how to implement some features. This Entity System is based off a bit from the Artemis framework, however it is different. I'm not sure if I'll be able to type this out the way my head processing it. I'm going to basically ask whether I should do something over something else. Okay, now I'll give a little detail on my Entity System itself. Here are the basic classes that my Entity System uses to actually work: Entity - An Id (and some methods to add/remove/get/etc Components) Component - An empty abstract class ComponentManager - Manages ALL components for ALL entities within a Scene EntitySystem - Processes entities with specific components Aspect - The class that is used to help determine what Components an Entity must contain so a specific EntitySystem can process it EntitySystemManager - Manages all EntitySystems within a Scene EntityManager - Manages entities (i.e. holds all Entities, used to determine whether an Entity has been changed, enables/disables them, etc.) EntityFactory - Creates (and destroys) entities and assigns an ID to them Scene - Contains an EntityManager, EntityFactory, EntitySystemManager and ComponentManager. Has functions to update and initialise the scene. Now in order for an EntitySystem to efficiently know when to check if an Entity is valid for processing (so I can add it to a specific EntitySystem), it must recieve a message from the EntityManager (after a call of activate(Entity& e)). Similarly the EntityManager must know when an Entity is destroyed from the EntityFactory in the Scene, and also the ComponentManager must know when an Entity is created AND destroyed. I do have a Listener/Observer pattern implemented at the moment, but with this pattern I may remove a Listener (which is this case is dependent on the method being called). I mainly have this implemented for specific things related to a game, i.e. Teams, Tagging of entities, etc. So... I was thinking maybe I should call a private method (using friend classes) to send out when an Entity has been activated, deleted, etc. i.e. taken from my EntityFactory void EntityFactory::killEntity(Entity& e) { // if the entity doesn't exsist in the entity manager within the scene if(!getScene()->getEntityManager().doesExsist(e)) { return; // go back to the caller! (should throw an exception or something..) } // tell the ComponentManager and the EntityManager that we killed an Entity getScene()->getComponentManager().doOnEntityWillDie(e); getScene()->getEntityManager().doOnEntityWillDie(e); // notify the listners for(Mouth::iterator i = getMouth().begin(); i != getMouth().end(); ++i) { (*i)->onEntityWillDie(*this, e); } _idPool.addId(e.getId()); // add the ID to the pool delete &e; // delete the entity } As you can see on the lines where I am telling the ComponentManager and the EntityManager that an Entity will die, I am calling a method to make sure it handles it appropriately. Now I realise I could do this without calling it explicitly, with the help of that for loop notifying all listener objects connected to the EntityFactory's Mouth (an object used to tell listeners that there's an event), however is this a good idea (good design, or what)? I've gone over the PROS and CONS, I just can't decide what I want to do. Calling Explicitly: PROS Faster? Since these functions are explicitly called, they can't be "removed" CONS Not flexible Bad design? (friend functions) Calling through Listener objects (i.e. ComponentManager/EntityManager inherits from a EntityFactoryListener) PROS More Flexible? Better Design? CONS Slower? (virtual functions) Listeners can be removed, i.e. may be removed and not get called again during the program, which could cause in a crash. P.S. If you wish to view my current source code, I am hosting it on BitBucket.

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• Object oriented wrapper around a dll

  - by Tom Davies

  So, I'm writing a C# managed wrapper around a native dll. The dll contains several hundred functions. In most cases, the first argument to each function is an opaque handle to a type internal to the dll. So, an obvious starting point for defining some classes in the wrapper would be to define classes corresponding to each of these opaque types, with each instance holding and managing the opaque handle (passed to its constructor) Things are a little awkward when dealing with callbacks from the dll. Naturally, the callback handlers in my wrapper have to be static, but the callbacks arguments invariable contain an opaque handle. In order to get from the static callback back to an object instance, I've created a static dictionary in each class, associating handles with class instances. In the constructor of each class, an entry is put into the dictionary, and this entry is then removed in the Destructors. When I receive a callback, I can then consult the dictionary to retrieve the class instance corresponding to the opaque reference. Are there any obvious flaws to this? Something that seems to be a problem is that the existence static dictionary means that the garbage collector will not act on my class instances that are otherwise unreachable. As they are never garbage collected, they never get removed from the dictionary, so the dictionary grows. It seems I might have to manually dispose of my objects, which is something absolutely would like to avoid. Can anyone suggest a good design that allows me to avoid having to do this?

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• How do we keep dependent data structures up to date?

  - by Geo

  Suppose you have a parse tree, an abstract syntax tree, and a control flow graph, each one logically derived from the one before. In principle it is easy to construct each graph given the parse tree, but how can we manage the complexity of updating the graphs when the parse tree is modified? We know exactly how the tree has been modified, but how can the change be propagated to the other trees in a way that doesn't become difficult to manage? Naturally the dependent graph can be updated by simply reconstructing it from scratch every time the first graph changes, but then there would be no way of knowing the details of the changes in the dependent graph. I currently have four ways to attempt to solve this problem, but each one has difficulties. Nodes of the dependent tree each observe the relevant nodes of the original tree, updating themselves and the observer lists of original tree nodes as necessary. The conceptual complexity of this can become daunting. Each node of the original tree has a list of the dependent tree nodes that specifically depend upon it, and when the node changes it sets a flag on the dependent nodes to mark them as dirty, including the parents of the dependent nodes all the way down to the root. After each change we run an algorithm that is much like the algorithm for constructing the dependent graph from scratch, but it skips over any clean node and reconstructs each dirty node, keeping track of whether the reconstructed node is actually different from the dirty node. This can also get tricky. We can represent the logical connection between the original graph and the dependent graph as a data structure, like a list of constraints, perhaps designed using a declarative language. When the original graph changes we need only scan the list to discover which constraints are violated and how the dependent tree needs to change to correct the violation, all encoded as data. We can reconstruct the dependent graph from scratch as though there were no existing dependent graph, and then compare the existing graph and the new graph to discover how it has changed. I'm sure this is the easiest way because I know there are algorithms available for detecting differences, but they are all quite computationally expensive and in principle it seems unnecessary so I'm deliberately avoiding this option. What is the right way to deal with these sorts of problems? Surely there must be a design pattern that makes this whole thing almost easy. It would be nice to have a good solution for every problem of this general description. Does this class of problem have a name?

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• Best software for taking a "System Information Snapshot"?

  - by djangofan

  I am curious what people would recommend as the best software for taking a system information snapshot? This would be for use in a technical support fashion.

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