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  • this pointer to base class constructor?

    - by Rolle
    I want to implement a derived class that should also implement an interface, that have a function that the base class can call. The following gives a warning as it is not safe to pass a this pointer to the base class constructor: struct IInterface { void FuncToCall() = 0; }; struct Base { Base(IInterface* inter) { m_inter = inter; } void SomeFunc() { inter->FuncToCall(); } IInterface* m_inter; }; struct Derived : Base, IInterface { Derived() : Base(this) {} FuncToCall() {} }; What is the best way around this? I need to supply the interface as an argument to the base constructor, as it is not always the dervied class that is the interface; sometimes it may be a totally different class. I could add a function to the base class, SetInterface(IInterface* inter), but I would like to avoid that.

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  • Class Mapping Error: 'T' must be a non-abstract type with a public parameterless constructor

    - by Amit Ranjan
    Hi, While mapping class i am getting error 'T' must be a non-abstract type with a public parameterless constructor in order to use it as parameter 'T' in the generic type or method. Below is my SqlReaderBase Class public abstract class SqlReaderBase<T> : ConnectionProvider { #region Abstract Methods protected abstract string commandText { get; } protected abstract CommandType commandType { get; } protected abstract Collection<IDataParameter> GetParameters(IDbCommand command); **protected abstract MapperBase<T> GetMapper();** #endregion #region Non Abstract Methods /// <summary> /// Method to Execute Select Queries for Retrieveing List of Result /// </summary> /// <returns></returns> public Collection<T> ExecuteReader() { //Collection of Type on which Template is applied Collection<T> collection = new Collection<T>(); // initializing connection using (IDbConnection connection = GetConnection()) { try { // creates command for sql operations IDbCommand command = connection.CreateCommand(); // assign connection to command command.Connection = connection; // assign query command.CommandText = commandText; //state what type of query is used, text, table or Sp command.CommandType = commandType; // retrieves parameter from IDataParameter Collection and assigns it to command object foreach (IDataParameter param in GetParameters(command)) command.Parameters.Add(param); // Establishes connection with database server connection.Open(); // Since it is designed for executing Select statements that will return a list of results // so we will call command's execute reader method that return a Forward Only reader with // list of results inside. using (IDataReader reader = command.ExecuteReader()) { try { // Call to Mapper Class of the template to map the data to its // respective fields MapperBase<T> mapper = GetMapper(); collection = mapper.MapAll(reader); } catch (Exception ex) // catch exception { throw ex; // log errr } finally { reader.Close(); reader.Dispose(); } } } catch (Exception ex) { throw ex; } finally { connection.Close(); connection.Dispose(); } } return collection; } #endregion } What I am trying to do is , I am executine some command and filling my class dynamically. The class is given below: namespace FooZo.Core { public class Restaurant { #region Private Member Variables private int _restaurantId = 0; private string _email = string.Empty; private string _website = string.Empty; private string _name = string.Empty; private string _address = string.Empty; private string _phone = string.Empty; private bool _hasMenu = false; private string _menuImagePath = string.Empty; private int _cuisine = 0; private bool _hasBar = false; private bool _hasHomeDelivery = false; private bool _hasDineIn = false; private int _type = 0; private string _restaurantImagePath = string.Empty; private string _serviceAvailableTill = string.Empty; private string _serviceAvailableFrom = string.Empty; public string Name { get { return _name; } set { _name = value; } } public string Address { get { return _address; } set { _address = value; } } public int RestaurantId { get { return _restaurantId; } set { _restaurantId = value; } } public string Website { get { return _website; } set { _website = value; } } public string Email { get { return _email; } set { _email = value; } } public string Phone { get { return _phone; } set { _phone = value; } } public bool HasMenu { get { return _hasMenu; } set { _hasMenu = value; } } public string MenuImagePath { get { return _menuImagePath; } set { _menuImagePath = value; } } public string RestaurantImagePath { get { return _restaurantImagePath; } set { _restaurantImagePath = value; } } public int Type { get { return _type; } set { _type = value; } } public int Cuisine { get { return _cuisine; } set { _cuisine = value; } } public bool HasBar { get { return _hasBar; } set { _hasBar = value; } } public bool HasHomeDelivery { get { return _hasHomeDelivery; } set { _hasHomeDelivery = value; } } public bool HasDineIn { get { return _hasDineIn; } set { _hasDineIn = value; } } public string ServiceAvailableFrom { get { return _serviceAvailableFrom; } set { _serviceAvailableFrom = value; } } public string ServiceAvailableTill { get { return _serviceAvailableTill; } set { _serviceAvailableTill = value; } } #endregion public Restaurant() { } } } For filling my class properties dynamically i have another class called MapperBase Class with following methods: public abstract class MapperBase<T> where T : new() { protected T Map(IDataRecord record) { T instance = new T(); string fieldName; PropertyInfo[] properties = typeof(T).GetProperties(); for (int i = 0; i < record.FieldCount; i++) { fieldName = record.GetName(i); foreach (PropertyInfo property in properties) { if (property.Name == fieldName) { property.SetValue(instance, record[i], null); } } } return instance; } public Collection<T> MapAll(IDataReader reader) { Collection<T> collection = new Collection<T>(); while (reader.Read()) { collection.Add(Map(reader)); } return collection; } } There is another class which inherits the SqlreaderBaseClass called DefaultSearch. Code is below public class DefaultSearch: SqlReaderBase<Restaurant> { protected override string commandText { get { return "Select Name from vw_Restaurants"; } } protected override CommandType commandType { get { return CommandType.Text; } } protected override Collection<IDataParameter> GetParameters(IDbCommand command) { Collection<IDataParameter> parameters = new Collection<IDataParameter>(); parameters.Clear(); return parameters; } protected override MapperBase<Restaurant> GetMapper() { MapperBase<Restaurant> mapper = new RMapper(); return mapper; } } But whenever I tried to build , I am getting error 'T' must be a non-abstract type with a public parameterless constructor in order to use it as parameter 'T' in the generic type or method. Even T here is Restaurant has a Parameterless Public constructor.

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  • A "Trig" Calculating Class

    - by Clinton Scott
    I have been trying to create a gui that calculates trigonometric functions based off of the user's input. I have had success in the GUI part, but my class that I wrote to hold information using inheritance seems to be messed up, because when I run it gives an error saying: Exception in thread "main" java.lang.RuntimeException: Uncompilable source code - constructor ArcTrigCalcCon in class TrigCalc.ArcTrigCalcCon cannot be applied to given types; required: double,double,double,double,double,double found: java.lang.Double,java.lang.Double,java.lang.Double reason: actual and formal argument lists differ in length at TrigCalc.TrigCalcGUI.(TrigCalcGUI.java:31) at TrigCalc.TrigCalcGUI.main(TrigCalcGUI.java:87) Java Result: 1 and says it is the object causing the problem. Below Will be my code. First I will put up my inheritance class with cosecant secant and cotangent and then my original class with the original 3 trig functions: { public ArcTrigCalcCon(double s, double cs, double t, double csc, double sc, double ct) { // Inherit from the Trig Calc class super(s, cs, t); cosecant = 1/s; secant = 1/cs; cotangent = 1/t; } public void setCsc(double csc) { cosecant = csc; } public void setSec(double sc) { secant = sc; } public void setCot(double ct) { cotangent = ct; } } Here is the first Trigonometric class: public class TrigCalcCon { public double sine; public double cosine; public double tangent; public TrigCalcCon(double s, double cs, double t) { sine = s; cosine = cs; tangent = t; } public void setSin(double s) { sine = s; } public void setCos(double cs) { cosine = cs; } public void setTan(double t) { tangent = t; } public void set(double s, double cs, double t) { sine = s; cosine = cs; tangent = t; } public double getSin() { return Math.sin(sine); } public double getCos() { return Math.cos(cosine); } public double getTan() { return Math.tan(tangent); } } and here is the demo class to run the gui: public class TrigCalcGUI extends JFrame implements ActionListener { // Instance Variables private String input; private Double s, cs, t, csc, sc, ct; private JPanel mainPanel, sinPanel, cosPanel, tanPanel, cscPanel, secPanel, cotPanel, buttonPanel, inputPanel, displayPanel; // Panel Display private JLabel sinLabel, cosLabel, tanLabel, secLabel, cscLabel, cotLabel, inputLabel; private JTextField sinTF, cosTF, tanTF, secTF, cscTF, cotTF, inputTF; //Text Fields for sin, cos, and tan, and inverse private JButton calcButton, clearButton; // Calculate and Exit Buttons // Object ArcTrigCalcCon trC = new ArcTrigCalcCon(s, cs, t); public TrigCalcGUI() { // title bar text. super("Trig Calculator"); // Corner exit button action. setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // Create main panel to add each panel to mainPanel = new JPanel(); mainPanel.setLayout(new GridLayout(3,2)); displayPanel = new JPanel(); displayPanel.setLayout(new GridLayout(3,2)); // Assign Panel to each variable inputPanel = new JPanel(); sinPanel = new JPanel(); cosPanel = new JPanel(); tanPanel = new JPanel(); cscPanel = new JPanel(); secPanel = new JPanel(); cotPanel = new JPanel(); buttonPanel = new JPanel(); // Call each constructor buildInputPanel(); buildSinCosTanPanels(); buildCscSecCotPanels(); buildButtonPanel(); // Add each panel to content pane displayPanel.add(sinPanel); displayPanel.add(cscPanel); displayPanel.add(cosPanel); displayPanel.add(secPanel); displayPanel.add(tanPanel); displayPanel.add(cotPanel); // Add three content panes to GUI mainPanel.add(inputPanel, BorderLayout.NORTH); mainPanel.add(displayPanel, BorderLayout.CENTER); mainPanel.add(buttonPanel, BorderLayout.SOUTH); //add mainPanel this.add(mainPanel); // size of window to content this.pack(); // display window setVisible(true); } public static void main(String[] args) { new TrigCalcGUI(); } private void buildInputPanel() { inputLabel = new JLabel("Enter a Value: "); inputTF = new JTextField(5); inputPanel.add(inputLabel); inputPanel.add(inputTF); } // Building Constructor for sinPanel cosPanel, and tanPanel private void buildSinCosTanPanels() { // Set layout and border for sinPanel sinPanel.setLayout(new GridLayout(2,2)); sinPanel.setBorder(BorderFactory.createTitledBorder("Sine")); // sinTF = new JTextField(5); sinTF.setEditable(false); sinPanel.add(sinTF); // Set layout and border for cosPanel cosPanel.setLayout(new GridLayout(2,2)); cosPanel.setBorder(BorderFactory.createTitledBorder("Cosine")); cosTF = new JTextField(5); cosTF.setEditable(false); cosPanel.add(cosTF); // Set layout and border for tanPanel tanPanel.setLayout(new GridLayout(2,2)); tanPanel.setBorder(BorderFactory.createTitledBorder("Tangent")); tanTF = new JTextField(5); tanTF.setEditable(false); tanPanel.add(tanTF); } // Building Constructor for cscPanel secPanel, and cotPanel private void buildCscSecCotPanels() { // Set layout and border for cscPanel cscPanel.setLayout(new GridLayout(2,2)); cscPanel.setBorder(BorderFactory.createTitledBorder("Cosecant")); // cscTF = new JTextField(5); cscTF.setEditable(false); cscPanel.add(cscTF); // Set layout and border for secPanel secPanel.setLayout(new GridLayout(2,2)); secPanel.setBorder(BorderFactory.createTitledBorder("Secant")); secTF = new JTextField(5); secTF.setEditable(false); secPanel.add(secTF); // Set layout and border for cotPanel cotPanel.setLayout(new GridLayout(2,2)); cotPanel.setBorder(BorderFactory.createTitledBorder("Cotangent")); cotTF = new JTextField(5); cotTF.setEditable(false); cotPanel.add(cotTF); } private void buildButtonPanel() { // Create buttons and add events calcButton = new JButton("Calculate"); calcButton.addActionListener(new CalcButtonListener()); clearButton = new JButton("Clear"); clearButton.addActionListener(new ClearButtonListener()); buttonPanel.add(calcButton); buttonPanel.add(clearButton); } @Override public void actionPerformed(ActionEvent e) { } private class CalcButtonListener implements ActionListener { public void actionPerformed(ActionEvent ae) { // Declare boolean variable boolean incorrect = true; // Set input variable to input text field text input = inputTF.getText(); ImageIcon newIcon; ImageIcon frowny = new ImageIcon(TrigCalcGUI.class.getResource("/Sad_Face.png")); Image gm = frowny.getImage(); Image newFrowny = gm.getScaledInstance(100, 100, java.awt.Image.SCALE_FAST); newIcon = new ImageIcon(newFrowny); // If boolean is true, throw exception if(incorrect) { try{Double.parseDouble(input); incorrect = false;} catch(NumberFormatException nfe) { String s = "Invalid Input " + "/n Input Must Be a Numerical value." + "/nPlease Press Ok and Try Again"; JOptionPane.showMessageDialog(null, s, "Invalid", JOptionPane.ERROR_MESSAGE, newIcon); inputTF.setText(""); inputTF.requestFocus(); } } // If boolean is not true, proceed with output if (incorrect != true) { /* Set each text field's output to the String double value * of inputTF */ sinTF.setText(input); cosTF.setText(input); tanTF.setText(input); cscTF.setText(input); secTF.setText(input); cotTF.setText(input); } } } /** * Private inner class that handles the event when * the user clicks the Exit button. */ private class ClearButtonListener implements ActionListener { public void actionPerformed(ActionEvent ae) { // Clear field sinTF.setText(""); cosTF.setText(""); tanTF.setText(""); cscTF.setText(""); secTF.setText(""); cotTF.setText(""); // Clear textfield and set cursor focus to field inputTF.setText(""); inputTF.requestFocus(); } } }

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  • add a div.class in a child, only when the parent does not have other div.class

    - by armandfp
    i have a html code like this: <div class="someclass"> <div class="childclass"></div> <div class="checkclass"></div> </div> <div class="someclass"> <div class="childclass"></div> </div> <div class="someclass"> <div class="childclass"></div> <div class="checkclass"></div> </div> <div class="someclass"> <div class="childclass"></div> <div class="checkclass"></div> </div> <div class="someclass"> <div class="childclass"></div> </div> and i need to add a div only on those divs that dont have that "checkclass", so it will like this: <div class="someclass"> <div class="childclass"></div> <div class="checkclass"></div> </div> <div class="someclass"> <div class="childclass"></div> <div class="newclass"></div> </div> <div class="someclass"> <div class="childclass"></div> <div class="checkclass"></div> </div> <div class="someclass"> <div class="childclass"></div> <div class="checkclass"></div> </div> <div class="someclass"> <div class="childclass"></div> <div class="newclass"></div> </div> i tried with jquery something like: $('.someclase:not(children(hasClass(checkclass))').append('<div class="newclass"></div>'); $('.someclass:not(:children(.checkclass))').append('<div class="newclass"></div>'); $('.someclass > :not(.checkclass)').append('<div class="newclass"></div>'); but still nothing, any ideas?

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  • Unique ID Defined by Most-Derived Class accessible through Base Class

    - by Narfanator
    Okay, so, the idea is that I have a map of "components", which inherit from componentBase, and are keyed on an ID unique to the most-derived*. Only, I can't think of a good way to get this to work. I tried it with the constructor, but that doesn't work (Maybe I did it wrong). The problem with any virtual, etc, inheritance tricks are that the user has to impliment them at the bottom, which can be forgotten and makes it less... clean. *Right phrase? If - is inheritance; foo is most-derived: foo-foo1-foo2-componentBase Here's some code showing the problem, and why CRTP can't cut it: (No, it's not legit code, but I'm trying to get my thoughts down) #include<map> class componentBase { public: virtual static char idFunction() = 0; }; template <class T> class component : public virtual componentBase { public: static char idFunction(){ return reinterpret_cast<char>(&idFunction); } }; class intermediateDerivations1 : public virtual component<intermediateDerivations1> { }; class intermediateDerivations2 : public virtual component<intermediateDerivations2> { }; class derived1 : public intermediateDerivations1 { }; class derived2 : public intermediateDerivations1 { }; //How the unique ID gets used (more or less) std::map<char, componentBase*> TheMap; template<class T> void addToMap(componentBase * c) { TheMap[T::idFunction()] = c; } template<class T> T * getFromMap() { return TheMap[T::idFunction()]; } int main() { //In each case, the key needs to be different. //For these, the CRTP should do it: getFromMap<intermediateDerivations1>(); getFromMap<intermediateDerivations2>(); //But not for these. getFromMap<derived1>(); getFromMap<derived2>(); return 0; } More or less, I need something that is always there, no matter what the user does, and has a sortable value that's unique to the most-derived class. Also, I realize this isn't the best-asked question, I'm actually having some unexpected difficultly wrapping my head around it in words, so ask questions if/when you need clarification.

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  • copy array from one class to another class array

    - by shishir.bobby
    hi all, i hv an array ("array A", which contains 3 objects, fox ex, to,from,message) in class "A". and in class "B",i m having another array ("array B"),which fills tableview,of class "B" only. i need to fill tableview,with the values of class A's array (i.e array A,with the object values, to,from,message). how can i do it?? how to copy array from another class ? i hope i m clear with my question regards shishir

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  • WPF - How to properly reference a class from XAML

    - by Andy T
    OK, this is a super super noob question, one that I'm almost embarrassed to ask... I want to reference a class in my XAML file. It's a DataTemplateSelector for selecting the right edit template for a DataGrid column. Anyway, I've written the class into my code behind, added the local namespace to the top of top of the XAML, but when I try to reference the class from the XAML, it tells me the class does not exist in the local namespace. I must be missing something really really simple but I just can't understand it... Here's my code. XAML: <Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:tk="http://schemas.microsoft.com/wpf/2008/toolkit" xmlns:local="clr-namespace:CustomFields" xmlns:col="clr-namespace:System.Collections;assembly=mscorlib" xmlns:sys="clr-namespace:System;assembly=mscorlib" x:Class="CustomFields.MainWindow" x:Name="Window" Title="Define Custom Fields" Width="425" Height="400" MinWidth="425" MinHeight="400"> <Window.Resources> <ResourceDictionary> <local:RangeValuesEditTemplateSelector> blah blah blah... </local:RangeValuesEditTemplateSelector> </ResourceDictionary> </Window.Resources> C#: namespace CustomFields { /// /// Interaction logic for MainWindow.xaml /// public partial class MainWindow : Window { public MainWindow() { this.InitializeComponent(); // Insert code required on object creation below this point. } } public class RangeValuesEditTemplateSelector : DataTemplateSelector { public RangeValuesEditTemplateSelector(){ MessageBox.Show("hello"); } } } Any ideas what I'm doing wrong? I thought this should be simple as 1-2-3... Thanks! AT

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  • how to match var/id to class

    - by circey
    Hi. I'm new to jquery and, in addition, I think I'm having a brain freeze. I have a number of links with different ids. I want to match the clicked link with a div with the corresponding class so the div will show/hide/toggle as appropriate. I have: <script type="text/javascript"> $(document).ready(function() { $('.folioBox').hide(); $('a.interface').click(function(){ var currentId = $(this).attr('id'); var currentBox = $('.folioBox .' + currentId); $(currentBox).toggle(400); }); }); </script> <a class="interface" id="apple">Apple flavor</a> <a class="interface" id="banana">Banana flavor</a> <a class="interface" id="cherry">Cherry flavor</a> <div class="folioBox apple">content</div> <div class="folioBox banana">content</div> <div class="folioBox cherry">content</div> I just can't get it to work and I can't figure out whether I would be best using match or find or filter. Some assistance would be much appreciated!

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  • Why do case class companion objects extend FunctionN?

    - by retronym
    When you create a case class, the compiler creates a corresponding companion object with a few of the case class goodies: an apply factory method matching the primary constructor, equals, hashCode, and copy. Somewhat oddly, this generated object extends FunctionN. scala> case class A(a: Int) defined class A scala> A: (Int => A) res0: (Int) => A = <function1> This is only the case if: There is no manually defined companion object There is exactly one parameter list There are no type arguments The case class isn't abstract. Seems like this was added about two years ago. The latest incarnation is here. Does anyone use this, or know why it was added? It increases the size of the generated bytecode a little with static forwarder methods, and shows up in the #toString() method of the companion objects: scala> case class A() defined class A scala> A.toString res12: java.lang.String = <function0>

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  • How do I use a variable within an extended class public variable

    - by Gerry Humphrey
    Have a class that I am using, I am overriding variables in the class to change them to what values I need, but I also not sure if or how to handle an issue. I need to add a key that is generated to each of this URLs before the class calls them. I cannot modify the class file itself. use Theme/Ride class ETicket extends Ride { public $key='US20120303'; // Not in original class public $accessURL1 = 'http://domain.com/keycheck.php?key='.$key; public $accessURL2 = 'http://domain.com/keycheck.php?key='.$key; } I understand that you cannot use a variable in the setting of the public class variables. Just not sure what would be the way to actually do something like this in the proper format. My OOP skills are weak. I admit it. So if someone has a suggestion on where I could read up on it and get a clue, it would be appreciated as well. I guess I need OOP for Dummies. =/

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  • Nested Class member function can't access function of enclosing class. Why?

    - by Rahul
    Please see the example code below: class A { private: class B { public: foobar(); }; public: foo(); bar(); }; Within class A & B implementation: A::foo() { //do something } A::bar() { //some code foo(); //more code } A::B::foobar() { //some code foo(); //<<compiler doesn't like this } The compiler flags the call to foo() within the method foobar(). Earlier, I had foo() as private member function of class A but changed to public assuming that B's function can't see it. Of course, it didn't help. I am trying to re-use the functionality provided by A's method. Why doesn't the compiler allow this function call? As I see it, they are part of same enclosing class (A). I thought the accessibility issue for nested class meebers for enclosing class in C++ standards was resolved. How can I achieve what I am trying to do without re-writing the same method (foo()) for B, which keeping B nested within A? I am using VC++ compiler ver-9 (Visual Studio 2008). Thank you for your help.

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  • :first-child fails when an element of a different class is dynamically inserted above

    - by koko
    So, I've encountered a situation where inserting an element of a different class/id breaks all css-rules on that :first-child. <div id="nav"> <div class="nSub">abcdef</div> <div class="nSub">abcdef</div> <div class="nSub">abcdef</div> <div class="nSub">abcdef</div> <div class="nSub">abcdef</div> </div> .nSub:first-child { margin-top:15px; -moz-border-radius-topleft:5px; /* ... */ } .nSub { background:#666; /* ... */ } .nSub:last-child { -moz-border-radius-bottomleft:5px; /* ... */ } As soon as I insert an element of another class/id above, like this: $('nav').insert({top:'<div id="newWF"></div>'}); all declarations for .nSub:first-child are being ignored in both FF 3.6 and Safari 4.

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  • Drawbacks with using Class Methods in Objective C.

    - by RickiG
    Hi I was wondering if there are any memory/performance drawbacks, or just drawbacks in general, with using Class Methods like: + (void)myClassMethod:(NSString *)param { // much to be done... } or + (NSArray*)myClassMethod:(NSString *)param { // much to be done... return [NSArray autorelease]; } It is convenient placing a lot of functionality in Class Methods, especially in an environment where I have to deal with memory management(iPhone), but there is usually a catch when something is convenient? An example could be a thought up Web Service that consisted of a lot of classes with very simple functionality. i.e. TomorrowsXMLResults; TodaysXMLResults; YesterdaysXMLResults; MondaysXMLResults; TuesdaysXMLResults; . . . n I collect a ton of these in my Web Service Class and just instantiate the web service class and let methods on this class call Class Methods on the 'Results' Classes. The classes are simple but they handle large amount of Xml, instantiate lots of objects etc. I guess I am asking if Class Methods lives or are treated different on the stack and in memory than messages to instantiated objects? Or are they just instantiated and pulled down again behind the scenes and thus, just a way of saving a few lines of code?

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  • Abstract base class puzzle

    - by 0x80
    In my class design I ran into the following problem: class MyData { int foo; }; class AbstraktA { public: virtual void A() = 0; }; class AbstraktB : public AbstraktA { public: virtual void B() = 0; }; template<class T> class ImplA : public AbstraktA { public: void A(){ cout << "ImplA A()"; } }; class ImplB : public ImplA<MyData>, public AbstraktB { public: void B(){ cout << "ImplB B()"; } }; void TestAbstrakt() { AbstraktB *b = (AbstraktB *) new ImplB; b->A(); b->B(); }; The problem with the code above is that the compiler will complain that AbstraktA::A() is not defined. Interface A is shared by multiple objects. But the implementation of A is dependent on the template argument. Interface B is the seen by the outside world, and needs to be abstrakt. The reason I would like this is that it would allow me to define object C like this: Define the interface C inheriting from abstrakt A. Define the implementation of C using a different datatype for template A. I hope I'm clear. Is there any way to do this, or do I need to rethink my design?

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  • How do I call +class methods in Objective C without referencing the class?

    - by TimM
    I have a series of "policy" objects which I thought would be convenient to implement as class methods on a set of policy classes. I have specified a protocol for this, and created classes to conform to (just one shown below) @protocol Counter +(NSInteger) countFor: (Model *)model; @end @interface CurrentListCounter : NSObject <Counter> +(NSInteger) countFor: (Model *)model; @end I then have an array of the classes that conform to this protocol (like CurrentListCounter does) +(NSArray *) availableCounters { return [[[NSArray alloc] initWithObjects: [CurrentListCounter class],[AllListsCounter class], nil] autorelease]; } Notice how I am using the classes like objects (and this might be my problem - in Smalltalk classes are objects like everything else - I'm not sure if they are in Objective-C?) My exact problem is when I want to call the method when I take one of the policy objects out of the array: id<Counter> counter = [[MyModel availableCounters] objectAtIndex: self.index]; return [counter countFor: self]; I get a warning on the return statement - it says -countFor: not found in protocol (so its assuming its an instance method where I want to call a class method). However as the objects in my array are instances of class, they are now like instance methods (or conceptually they should be). Is there a magic way to call class methods? Or is this just a bad idea and I should just create instances of my policy objects (and not use class methods)?

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  • Unable to Get values from Web Form to a PHP Class to Display

    - by kentrenholm
    I am having troubles getting the value from my variables submitted via a web form using a PHP class file. Here is my structure of the web page: Order Form Page Process.php Page Book.php Page I can easily get the user data entered (on Order Form Page), process, and display it on the Process.php page. The issue is that I must create a Book class and print the details of the data using the Book class. I have an empty constructor printing out "created" so I know my constructor is being called. I also am able to print the word "title" so I know I can print to the screen by using the Book class. My issue is that I can't get values in my variables in the Book class. Here is my variable declaration: private $title; Here is my printDetails function: public function printDetails () { echo "Title: " . $this->title . "<br />"; } Here is my new instance of the book class: $bookNow = new book; Here are my get and set functions: function __getTitle($title) { return $this->$title; } function __setTitle($title,$value) { $this->$title = $value; } I do have four other variables that I'm looking to display as well. Each of those have their own variable declaration, a line in printDetails, and their own setter and getter. Lastly, I also have a call to the Book class in my process PHP. It looks like this: function __autoload($book) { include $book . '.php'; } $bookNow = new book(); Any help, much appreciated. It must be something so very small (I'm hoping).

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  • How do you overide a class that is called by another class with parent::method

    - by dan.codes
    I am trying to extend Mage_Catalog_Block_Product_View I have it setup in my local directory as its own module and everything works fine, I wasn't getting the results that I wanted. I then saw that another class extended that class as well. The method I am trying to override is the protected function _prepareLayout() This is the function class Mage_Review_Block_Product_View extends Mage_Catalog_Block_Product_View protected function _prepareLayout() { $this-&gt;getLayout()-&gt;createBlock('catalog/breadcrumbs'); $headBlock = $this-&gt;getLayout()-&gt;getBlock('head'); if ($headBlock) { $title = $this-&gt;getProduct()-&gt;getMetaTitle(); if ($title) { $headBlock-&gt;setTitle($title); } $keyword = $this-&gt;getProduct()-&gt;getMetaKeyword(); $currentCategory = Mage::registry('current_category'); if ($keyword) { $headBlock-&gt;setKeywords($keyword); } elseif($currentCategory) { $headBlock-&gt;setKeywords($this-&gt;getProduct()-&gt;getName()); } $description = $this-&gt;getProduct()-&gt;getMetaDescription(); if ($description) { $headBlock-&gt;setDescription( ($description) ); } else { $headBlock-&gt;setDescription( $this-&gt;getProduct()-&gt;getDescription() ); } } return parent::_prepareLayout(); } I am trying to modify it just a bit with the following, keep in mind I know there is a title prefix and suffix but I needed it only for the product page and also I needed to add text to the description. class MyCompany_Catalog_Block_Product_View extends Mage_Catalog_Block_Product_View protected function _prepareLayout() { $storeId = Mage::app()-&gt;getStore()-&gt;getId(); $this-&gt;getLayout()-&gt;createBlock('catalog/breadcrumbs'); $headBlock = $this-&gt;getLayout()-&gt;getBlock('head'); if ($headBlock) { $title = $this-&gt;getProduct()-&gt;getMetaTitle(); if ($title) { if($storeId == 2){ $title = "Pool Supplies Fast - " .$title; $headBlock-&gt;setTitle($title); } $headBlock-&gt;setTitle($title); }else{ $path = Mage::helper('catalog')-&gt;getBreadcrumbPath(); foreach ($path as $name =&gt; $breadcrumb) { $title[] = $breadcrumb['label']; } $newTitle = "Pool Supplies Fast - " . join($this-&gt;getTitleSeparator(), array_reverse($title)); $headBlock-&gt;setTitle($newTitle); } $keyword = $this-&gt;getProduct()-&gt;getMetaKeyword(); $currentCategory = Mage::registry('current_category'); if ($keyword) { $headBlock-&gt;setKeywords($keyword); } elseif($currentCategory) { $headBlock-&gt;setKeywords($this-&gt;getProduct()-&gt;getName()); } $description = $this-&gt;getProduct()-&gt;getMetaDescription(); if ($description) { if($storeId == 2){ $description = "Pool Supplies Fast - ". $this-&gt;getProduct()-&gt;getName() . " - " . $description; $headBlock-&gt;setDescription( ($description) ); }else{ $headBlock-&gt;setDescription( ($description) ); } } else { if($storeId == 2){ $description = "Pool Supplies Fast: ". $this-&gt;getProduct()-&gt;getName() . " - " . $this-&gt;getProduct()-&gt;getDescription(); $headBlock-&gt;setDescription( ($description) ); }else{ $headBlock-&gt;setDescription( $this-&gt;getProduct()-&gt;getDescription() ); } } } return Mage_Catalog_Block_Product_Abstract::_prepareLayout(); } This executs fine but then I notice that the following class Mage_Review_Block_Product_View_List extends which extends Mage_Review_Block_Product_View and that extends Mage_Catalog_Block_Product_View as well. Inside this class they call the _prepareLayout as well and call the parent with parent::_prepareLayout() class Mage_Review_Block_Product_View_List extends Mage_Review_Block_Product_View protected function _prepareLayout() { parent::_prepareLayout(); if ($toolbar = $this-&gt;getLayout()-&gt;getBlock('product_review_list.toolbar')) { $toolbar-&gt;setCollection($this-&gt;getReviewsCollection()); $this-&gt;setChild('toolbar', $toolbar); } return $this; } So obviously this just calls the same class I am extending and runs the function I am overiding but it doesn't get to my class because it is not in my class hierarchy and since it gets called after my class all the stuff in the parent class override what I have set. I'm not sure about the best way to extend this type of class and method, there has to be a good way to do this, I keep finding I am running into issues when trying to overide these prepare methods that are derived from the abstract classes, there seems to be so many classes overriding them and calling parent::method. What is the best way to override these functions?

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  • Get class instance by class name string

    - by VDVLeon
    Hi all, I noticed the function Object.factory(char[] className) in D. But it does not work like I hoped it would work; it does not work ;) An example: import std.stdio; class TestClass { override string toString() { return typeof(this).stringof; // TestClass } }; void main(string[] args) { auto i = Object.factory("TestClass"); if (i is null) { writeln("Class not found"); } else { writeln("Class string: " ~ i); } } I think this should result in the message: "Class string: TestClass" but it says "Class not found". Does anybody know why this happens and how I could fix it ? Or do I need to make my own class factory. For example by make a class with a static array Object[string] classes; with class instances. When I want a new instance I do this: auto i = (className in classes); if (i is null) { return null; } return i.classinfo.create();

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  • jQuery - toggle the class of a parent element?

    - by Nike
    Hello, again. I have a few list elements, like this: <li class="item"> <a class="toggle"><h4>ämne<small>2010-04-17 kl 12:54 by <u>nike1</u></small></h4></a> <div class="meddel"> <span> <img style="max-width: 70%; min-height: 70%;" src="profile-images/nike1.jpg" alt="" /> <a href="account.php?usr=47">nike1</a> </span> <p>text</p> <span style="clear: both; display: block;"></span> </div> </li> <li class="item odd"> <a class="toggle"><h4>test<small>2010-04-17 kl 15:01 by <u>nike1</u></small></h4></a> <div class="meddel"> <span> <img style="max-width: 70%; min-height: 70%;" src="profile-images/nike1.jpg" alt="" /> <a href="account.php?usr=47">nike1</a> </span> <p>test meddelande :) [a]http://youtube.com[/a]</p> <span style="clear: both; display: block;"></span> </div> </li> And i'm trying to figure out how to make it so that when you click a link with the class .toggle, the parent element (the li element) will toggle the class .current. I'm not sure if the following code is correct or not, but it's not working. $(this).parent('.item').toggleClass('.current', addOrRemove); Even if i remove "('.item')", it doesn't seem to make any difference. So, any ideas? Thanks in advance, -Nike

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  • Mootools - how to destroy a class instance

    - by Rob
    What I'm trying to do is create a class that I can quickly attach to links, that will fetch and display a thumbnail preview of the document being linked to. Now, I am focusing on ease of use and portability here, I want to simply add a mouseover event to links like this: <a href="some-document.pdf" onmouseover="new TestClass(this)">Testing</a> I realize there are other ways I can go about this that would solve my issue here, and I may end up having to do that, but right now my goal is to implement this as above. I don't want to manually add a mouseout event to each link, and I don't want code anywhere other than within the class (and the mouseover event creating the class instance). The code: TestClass = new Class({ initialize: function(anchor) { this.anchor = $(anchor); if(!this.anchor) return; if(!window.zzz) window.zzz = 0; this.id = ++window.zzz; this.anchor.addEvent('mouseout', function() { // i need to get a reference to this function this.hide(); }.bind(this)); this.show(); }, show: function() { // TODO: cool web 2.0 stuff here! }, hide: function() { alert(this.id); //this.removeEvent('mouseout', ?); // need reference to the function to remove /*** this works, but what if there are unrelated mouseout events? and the class instance still exists! ***/ //this.anchor.removeEvents('mouseout'); //delete(this); // does not work ! //this = null; // invalid assignment! //this = undefined; // invalid assignment! } }); What currently happens with the above code: 1st time out: alerts 1 2nd time out: alerts 1, 2 3rd time out: alerts 1, 2, 3 etc Desired behavior: 1st time out: alerts 1 2nd time out: alerts 2 3rd time out: alerts 3 etc The problem is, each time I mouse over the link, I'm creating a new class instance and appending a new mouseout event for that instance. The class instance also remains in memory indefinitely. On mouseout I need to remove the mouseout event and destroy the class instance, so on subsequent mouseovers we are starting fresh.

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  • How to move a struct into a class?

    - by Kache4
    I've got something like: typedef struct Data_s { int field1; int field2; } Data; class Foo { void useData(Data& data); } Is there a way to move the struct into the class without creating a new class? Currently, just pasting it inside the class and replacing Data with Foo::Data everywhere doesn't work.

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  • Python class decorator and maximum recursion depth exceeded

    - by Michal Lula
    I try define class decorator. I have problem with __init__ method in decorated class. If __init__ method invokes super the RuntimeError maximum recursion depth exceeded is raised. Code example: def decorate(cls): class NewClass(cls): pass return NewClass @decorate class Foo(object): def __init__(self, *args, **kwargs): super(Foo, self).__init__(*args, **kwargs) What I doing wrong? Thanks, Michal

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