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• overriding implemented base class methods

  - by user793468

  I read somewhere that the chain of inheritance breaks when you alter a behavior from derived class. What does "altering a behavior" mean here? Is overriding an already implemented method in base class considered as "altering behavior"? Or, does the author mean altering method signatures and the output? Also, I ready Duplicating code is not a good practice, and its a maintenance nightmare. Again, does overriding an already implemented method in base class considered "Duplicating code"? If not, what would be considered as "Duplicating code"? I

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• How to ensure that a member variable is initialized before calling a class method

  - by Omkar Ekbote

  There's a class with a parametrized constructor that initializes a member variable. All public methods of the class then use this member variable to do something. I want to ensure that the caller always creates an object using the parametrized constructor (there is also a setter for this member variable) and then call that object's methods. In essence, it should be impossible for the caller to call any method without setting a value to the member variable (either by using the parametrized constructor or the setter). Currently, a caller can simply make an object using the default constructor and then call that object's method - I want to avoid checking whether or not the member variable is set in each and every one of the 20-odd methods of the class (and throw an exception if it is not). Though a runtime solution is acceptable (better than the one I mentioned above); a compile-time solution is preferable so that any developer will not be allowed to make that mistake and then waste hours debuggging it!

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• Why is it good to split a program into multiple classes?

  - by user1276078

  I'm still a student in high school (entering 10th grade), and I have yet to take an actual computer course in school. Everything I've done so far is through books. Those books have taught me concepts such as inheritance, but how does splitting a program into multiple classes help? The books never told me. I'm asking this mainly because of a recent project. It's an arcade video game, sort of like a flash game as some people have said (although I have no idea what a flash game is). The thing is, it's only one class. It works perfectly fine (a little occasional lag however) with just one class. So, I'm just asking how splitting it into multiple classes would help it. This project was in JAVA and I am the only person working on it, for the record.

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• Should single purpose utility app use a class

  - by jmoreno

  When writing a small utility app, that does just one thing, should that one thing be encapsulated in a seperate class, or just let it be part of whatever class/module is used to start the application? I.e. Main would consist of 2 or three lines calling the constructor and then the DoIt methods, nothing else. Or should Main be the DoIt method, with whatever functions it needs added to the main class? Asking because I want to get some alternative perspective, but couldn't find a similar question. If my google-fu is bad and there's a dup, please close.

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• Should Equality be commutative within a Class Hierachy?

  - by vossad01

  It is easy to define the Equals operation in ways that are not commutative. When providing equality against other types, there are obviously situations (in most languages) were equality not being commutative is unavoidable. However, within one's own inheritance hierarchy where the root base class defines an equality member, a programmer has more control. Thus you can create situations where (A = B) ? (B = A), where A and B both derive from base class T Substituting the = with the appropriate variation for a given language. (.Equals(_), ==, etc.) That seems wrong to me, however, I recognize I may be biased by background in Mathematics. I have not been in programming long enough to know what is standard/accepted/preferred practice when programming. Do most programmers just accept .Equals(_)may not be commutative and code defensibly. Do they expect commutativity and get annoyed if it is not. In short, when working in a class hierarchy, should effort me made to ensure Equality is commutative?

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• Can't remove JPanel from JFrame while adding new class into it

  - by A.K.

  Basically, I have my Frame class, which instantiates all the properties for the JFrame, and draws a JLabel with an image (my title screen). Then I made a separate JPanel with a start button on it, and made a mouse listener that will allow me to remove these objects while adding in a new Board() class (Which paints the main game). *Note: The JLabel is SEPARATE from the JPanel, but it still gets moved to the side by it. Problem: Whenever I click the button though, it only shows a little square of what I presume is my board class trying to run. Code below for the Frame Class: package OurPackage; //Made By A.K. 5/24/12 //Contains Frame. import java.awt.BorderLayout; import java.awt.Color; import java.awt.Container; import java.awt.Dimension; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.GridBagLayout; import java.awt.GridLayout; import java.awt.Image; import java.awt.Rectangle; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.KeyEvent; import java.awt.event.MouseAdapter; import java.awt.event.MouseEvent; import java.awt.event.MouseListener; import javax.swing.*; import javax.swing.plaf.basic.BasicOptionPaneUI.ButtonActionListener; public class Frame implements MouseListener { public static boolean StartGame = false; ImageIcon img = new ImageIcon(getClass().getResource("/Images/ActionJackTitle.png")); ImageIcon StartImg = new ImageIcon(getClass().getResource("/Images/JackStart.png")); public Image Title; JLabel TitleL = new JLabel(img); public JPanel panel = new JPanel(); JButton StartB = new JButton(StartImg); JFrame frm = new JFrame("Action-Packed Jack"); public Frame() { TitleL.setPreferredSize(new Dimension(1200, 420)); frm.add(TitleL); frm.setLayout(new GridBagLayout()); frm.add(panel); panel.setSize(new Dimension(220, 45)); panel.setLayout(new GridBagLayout ()); panel.add(StartB); StartB.addMouseListener(this); StartB.setPreferredSize(new Dimension(220, 45)); frm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frm.setSize(1200, 420); frm.setVisible(true); frm.setResizable(false); frm.setLocationRelativeTo(null); } public static void main(String[] args) { new Frame(); } public void mouseClicked(MouseEvent e) { StartB.setContentAreaFilled(false); panel.remove(StartB); frm.remove(panel); frm.remove(TitleL); //frm.setLayout(null); frm.add(new Board()); //Add Game "Tiles" Or Content. x = 1200 frm.validate(); System.out.println("Hit!"); } @Override public void mouseEntered(MouseEvent arg0) { // TODO Auto-generated method stub } @Override public void mouseExited(MouseEvent arg0) { // TODO Auto-generated method stub } @Override public void mousePressed(MouseEvent arg0) { // TODO Auto-generated method stub } @Override public void mouseReleased(MouseEvent arg0) { // TODO Auto-generated method stub } }

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• How to layout class definition when inheriting from multiple interfaces

  - by gabr

  Given two interface definitions ... IOmniWorkItem = interface ['{3CE2762F-B7A3-4490-BF22-2109C042EAD1}'] function GetData: TOmniValue; function GetResult: TOmniValue; function GetUniqueID: int64; procedure SetResult(const value: TOmniValue); // procedure Cancel; function DetachException: Exception; function FatalException: Exception; function IsCanceled: boolean; function IsExceptional: boolean; property Data: TOmniValue read GetData; property Result: TOmniValue read GetResult write SetResult; property UniqueID: int64 read GetUniqueID; end; IOmniWorkItemEx = interface ['{3B48D012-CF1C-4B47-A4A0-3072A9067A3E}'] function GetOnWorkItemDone: TOmniWorkItemDoneDelegate; function GetOnWorkItemDone_Asy: TOmniWorkItemDoneDelegate; procedure SetOnWorkItemDone(const Value: TOmniWorkItemDoneDelegate); procedure SetOnWorkItemDone_Asy(const Value: TOmniWorkItemDoneDelegate); // property OnWorkItemDone: TOmniWorkItemDoneDelegate read GetOnWorkItemDone write SetOnWorkItemDone; property OnWorkItemDone_Asy: TOmniWorkItemDoneDelegate read GetOnWorkItemDone_Asy write SetOnWorkItemDone_Asy; end; ... what are your ideas of laying out class declaration that inherits from both of them? My current idea (but I don't know if I'm happy with it): TOmniWorkItem = class(TInterfacedObject, IOmniWorkItem, IOmniWorkItemEx) strict private FData : TOmniValue; FOnWorkItemDone : TOmniWorkItemDoneDelegate; FOnWorkItemDone_Asy: TOmniWorkItemDoneDelegate; FResult : TOmniValue; FUniqueID : int64; strict protected procedure FreeException; protected //IOmniWorkItem function GetData: TOmniValue; function GetResult: TOmniValue; function GetUniqueID: int64; procedure SetResult(const value: TOmniValue); protected //IOmniWorkItemEx function GetOnWorkItemDone: TOmniWorkItemDoneDelegate; function GetOnWorkItemDone_Asy: TOmniWorkItemDoneDelegate; procedure SetOnWorkItemDone(const Value: TOmniWorkItemDoneDelegate); procedure SetOnWorkItemDone_Asy(const Value: TOmniWorkItemDoneDelegate); public constructor Create(const data: TOmniValue; uniqueID: int64); destructor Destroy; override; public //IOmniWorkItem procedure Cancel; function DetachException: Exception; function FatalException: Exception; function IsCanceled: boolean; function IsExceptional: boolean; property Data: TOmniValue read GetData; property Result: TOmniValue read GetResult write SetResult; property UniqueID: int64 read GetUniqueID; public //IOmniWorkItemEx property OnWorkItemDone: TOmniWorkItemDoneDelegate read GetOnWorkItemDone write SetOnWorkItemDone; property OnWorkItemDone_Asy: TOmniWorkItemDoneDelegate read GetOnWorkItemDone_Asy write SetOnWorkItemDone_Asy; end; As noted in answers, composition is a good approach for this example but I'm not sure it applies in all cases. Sometimes I'm using multiple inheritance just to split read and write access to some property into public (typically read-only) and private (typically write-only) part. Does composition still apply here? I'm not really sure as I would have to move the property in question out from the main class and I'm not sure that's the correct way to do it. Example: // public part of the interface interface IOmniWorkItemConfig = interface function OnExecute(const aTask: TOmniBackgroundWorkerDelegate): IOmniWorkItemConfig; function OnRequestDone(const aTask: TOmniWorkItemDoneDelegate): IOmniWorkItemConfig; function OnRequestDone_Asy(const aTask: TOmniWorkItemDoneDelegate): IOmniWorkItemConfig; end; // private part of the interface IOmniWorkItemConfigEx = interface ['{42CEC5CB-404F-4868-AE81-6A13AD7E3C6B}'] function GetOnExecute: TOmniBackgroundWorkerDelegate; function GetOnRequestDone: TOmniWorkItemDoneDelegate; function GetOnRequestDone_Asy: TOmniWorkItemDoneDelegate; end; // implementing class TOmniWorkItemConfig = class(TInterfacedObject, IOmniWorkItemConfig, IOmniWorkItemConfigEx) strict private FOnExecute : TOmniBackgroundWorkerDelegate; FOnRequestDone : TOmniWorkItemDoneDelegate; FOnRequestDone_Asy: TOmniWorkItemDoneDelegate; public constructor Create(defaults: IOmniWorkItemConfig = nil); public //IOmniWorkItemConfig function OnExecute(const aTask: TOmniBackgroundWorkerDelegate): IOmniWorkItemConfig; function OnRequestDone(const aTask: TOmniWorkItemDoneDelegate): IOmniWorkItemConfig; function OnRequestDone_Asy(const aTask: TOmniWorkItemDoneDelegate): IOmniWorkItemConfig; public //IOmniWorkItemConfigEx function GetOnExecute: TOmniBackgroundWorkerDelegate; function GetOnRequestDone: TOmniWorkItemDoneDelegate; function GetOnRequestDone_Asy: TOmniWorkItemDoneDelegate; end;

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• Is my class structure good enough?

  - by Rivten

  So I wanted to try out this challenge on reddit which is mostly about how you structure your data the best you can. I decided to challenge my C++ skills. Here's how I planned this. First, there's the Game class. It deals with time and is the only class main has access to. A game has a Forest. For now, this class does not have a lot of things, only a size and a Factory. Will be put in better use when it will come to SDL-stuff I guess A Factory is the thing that deals with the Game Objects (a.k.a. Trees, Lumberjack and Bears). It has a vector of all GameObjects and a queue of Events which will be managed at the end of one month. A GameObject is an abstract class which can be updated and which can notify the Event Listener The EventListener is a class which handles all the Events of a simulation. It can recieve events from a Game Object and notify the Factory if needed, the latter will manage correctly the event. So, the Tree, Lumberjack and Bear classes all inherits from GameObject. And Sapling and Elder Tree inherits from Tree. Finally, an Event is defined by an event_type enumeration (LUMBERJACK_MAWED, SAPPLING_EVOLUTION, ...) and an event_protagonists union (a GameObject or a pair of GameObject (who killed who ?)). I was quite happy at first with this because it seems quite logic and flexible. But I ended up questionning this structure. Here's why : I dislike the fact that a GameObject need to know about the Factory. Indeed, when a Bear moves somewhere, it needs to know if there's a Lumberjack ! Or it is the Factory which handles places and objects. It would be great if a GameObject could only interact with the EventListener... or maybe it's not that much of a big deal. Wouldn't it be better if I separate the Factory in three vectors ? One for each kind of GameObject. The idea would be to optimize research. If I'm looking do delete a dead lumberjack, I would only have to look in one shorter vector rather than a very long vector. Another problem arises when I want to know if there is any particular object in a given case because I have to look for all the gameObjects and see if they are at the given case. I would tend to think that the other idea would be to use a matrix but then the issue would be that I would have empty cases (and therefore unused space). I don't really know if Sapling and Elder Tree should inherit from Tree. Indeed, a Sapling is a Tree but what about its evolution ? Should I just delete the sapling and say to the factory to create a new Tree at the exact same place ? It doesn't seem natural to me to do so. How could I improve this ? Is the design of an Event quite good ? I've never used unions before in C++ but I didn't have any other ideas about what to use. Well, I hope I have been clear enough. Thank you for taking the time to help me !

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• Where are config files for class libraries physically located?

  - by BadNinja

  My guess is that this question will fall under the category of "duh", but, nevertheless, I'm confused. When using config files in, for example, a Windows Forms Application, the config file can be found in C:\Program files\CompanyName\ProductName\Application.exe.config. However, with the class library I'm developing I do not see a "ClassLibrary.dll.config" file in the install folder after installing it (in tandem with another project) from Visual Studio. Even though I do not see the file anywhere, retrieving data from it works correctly. Plus, running the following code from a method within the class library returns the path you would expect: C:\Program files\CompanyName\ProductName\ClassLibrary.dll.config. If someone could shed some light on what I'm missing here, that would be really awesome. public static string MyMethod() { Assembly assem = Assembly.GetExecutingAssembly(); Configuration config = ConfigurationManager.OpenExeConfiguration(assem.Location); return "The assembly location was: " + assem.Location + Environment.NewLine + "The config file path was: " + config.FilePath; // Gives me "C:\Program files\CompanyName\ProductName\ClassLibrary.dll.config" }

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• Inherit a parent class docstring as __doc__ attribute

  - by Reinout van Rees

  There is a question about Inherit docstrings in Python class inheritance, but the answers there deal with method docstrings. My question is how to inherit a docstring of a parent class as the __doc__ attribute. The usecase is that Django rest framework generates nice documentation in the html version of your API based on your view classes' docstrings. But when inheriting a base class (with a docstring) in a class without a docstring, the API doesn't show the docstring. It might very well be that sphinx and other tools do the right thing and handle the docstring inheritance for me, but django rest framework looks at the (empty) .__doc__ attribute. class ParentWithDocstring(object): """Parent docstring""" pass class SubClassWithoutDoctring(ParentWithDocstring): pass parent = ParentWithDocstring() print parent.__doc__ # Prints "Parent docstring". subclass = SubClassWithoutDoctring() print subclass.__doc__ # Prints "None" I've tried something like super(SubClassWithoutDocstring, self).__doc__, but that also only got me a None.

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• need to print 5 column list in alpha order, vertically

  - by Brad

  Have a webpage that will be viewed by mainly IE users, so CSS3 is out of the question. I want it to list like: A D G B E H C F I Here is the function that currently lists like: A B C D E F G H I function listPhoneExtensions($group,$group_title) { $adldap = new adLDAP(); $group_membership = $adldap->group_members(strtoupper($group),FALSE); sort($group_membership); print " <a name=\"".strtolower($group_title)."\"></a> <h2>".$group_title."</h2> <ul class=\"phone-extensions\">"; foreach ($group_membership as $i => $username) { $userinfo = $adldap->user_info($username, array("givenname","sn","telephonenumber")); $displayname = "<span class=\"name\">".substr($userinfo[0]["sn"][0],0,9).", ".substr($userinfo[0]["givenname"][0],0,9)."</span><span class=\"ext\">".$userinfo[0]["telephonenumber"][0]."</span>"; if($userinfo[0]["sn"][0] != "" && $userinfo[0]["givenname"][0] != "" && $userinfo[0]["telephonenumber"][0] != "") { print "<li>".$displayname."</li>"; } } print "</ul><p class=\"clear-both\"><a href=\"#top\" class=\"link-to-top\">&uarr; top</a></p>"; } Example rendered html: <ul class="phone-extensions"> <li><span class="name">Barry Bonds</span><span class="ext">8281</span></li> <li><span class="name">Gerald Clark</span><span class="ext">8211</span></li> <li><span class="name">Juan Dixon</span><span class="ext">8282</span></li> <li><span class="name">Omar Ebbs</span><span class="ext">8252</span></li> <li><span class="name">Freddie Flank</span><span class="ext">2281</span></li> <li><span class="name">Jerry Gilmore</span><span class="ext">4231</span></li> <li><span class="name">Kim Moore</span><span class="ext">5767</span></li> <li><span class="name">Barry Bonds</span><span class="ext">8281</span></li> <li><span class="name">Gerald Clark</span><span class="ext">8211</span></li> <li><span class="name">Juan Dixon</span><span class="ext">8282</span></li> <li><span class="name">Omar Ebbs</span><span class="ext">8252</span></li> <li><span class="name">Freddie Flank</span><span class="ext">2281</span></li> <li><span class="name">Jerry Gilmore</span><span class="ext">4231</span></li> <li><span class="name">Kim Moore</span><span class="ext">5767</span></li> <li><span class="name">Barry Bonds</span><span class="ext">8281</span></li> <li><span class="name">Gerald Clark</span><span class="ext">8211</span></li> <li><span class="name">Juan Dixon</span><span class="ext">8282</span></li> <li><span class="name">Omar Ebbs</span><span class="ext">8252</span></li> <li><span class="name">Freddie Flank</span><span class="ext">2281</span></li> <li><span class="name">Jerry Gilmore</span><span class="ext">4231</span></li> <li><span class="name">Kim Moore</span><span class="ext">5767</span></li> </ul> Any help is appreciated to getting it to list alpha vertically.

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• CorePlot linker errors after upgrading iOS SDK

  - by JustinXXVII

  This seems like it's happened before but somehow ended up working itself out. It's happened again and I can't seem to get this fixed. I use the CorePlot Cocoa Touch framework. Everything was fine until I upgraded to the new 4.3 beta. Now my project won't compile, and is giving me linker errors for unknown symbols having to do with CorePlot. I've become a pro at adding the framework to my project, and I've checked and rechecked the instructions trying to do it again. Is there a button I can click or anything to just make this work again? I've used these instructions to try to re-add the framework, to no avail EDIT: By the way, this compiles just fine for simulator and runs graphs no problem. Compiling for the device gives me the linker errors, as follows: "_OBJC_CLASS_$_CPPlotRange", referenced from: objc-class-ref in GraphStatsWindow.o objc-class-ref in iPadGraphView.o objc-class-ref in GraphTrendView.o "_OBJC_CLASS_$_CPXYGraph", referenced from: objc-class-ref in GraphStatsWindow.o objc-class-ref in iPadGraphView.o objc-class-ref in GraphTrendView.o "_OBJC_CLASS_$_CPTextStyle", referenced from: objc-class-ref in GraphStatsWindow.o objc-class-ref in iPadGraphView.o objc-class-ref in GraphTrendView.o "_OBJC_CLASS_$_CPLineStyle", referenced from: objc-class-ref in GraphStatsWindow.o objc-class-ref in iPadGraphView.o objc-class-ref in GraphTrendView.o "_OBJC_CLASS_$_CPScatterPlot", referenced from: objc-class-ref in GraphStatsWindow.o objc-class-ref in iPadGraphView.o objc-class-ref in GraphTrendView.o "_OBJC_CLASS_$_CPAxisLabel", referenced from: objc-class-ref in GraphStatsWindow.o objc-class-ref in iPadGraphView.o objc-class-ref in GraphTrendView.o "_OBJC_CLASS_$_CPPlotSymbol", referenced from: objc-class-ref in GraphStatsWindow.o objc-class-ref in iPadGraphView.o objc-class-ref in GraphTrendView.o "_OBJC_CLASS_$_CPColor", referenced from: objc-class-ref in GraphStatsWindow.o objc-class-ref in iPadGraphView.o objc-class-ref in GraphTrendView.o "_OBJC_CLASS_$_CPFill", referenced from: objc-class-ref in GraphStatsWindow.o objc-class-ref in iPadGraphView.o objc-class-ref in GraphTrendView.o "_CPDecimalFromFloat", referenced from: -[GraphStatsWindow setNewGraph] in GraphStatsWindow.o -[iPadGraphView viewDidLoad] in iPadGraphView.o -[GraphTrendView setNewGraph] in GraphTrendView.o "_kCPPlainWhiteTheme", referenced from: -[GraphStatsWindow setNewGraph] in GraphStatsWindow.o -[iPadGraphView viewDidLoad] in iPadGraphView.o -[GraphTrendView setNewGraph] in GraphTrendView.o "_OBJC_CLASS_$_CPTheme", referenced from: objc-class-ref in GraphStatsWindow.o objc-class-ref in iPadGraphView.o objc-class-ref in GraphTrendView.o ld: symbol(s) not found for architecture armv7

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• VS 2010 Class Diagram Error "The type cannot be edited..."

  - by Eric J.

  A few of the classes on a VS 2010 class diagram are displayed with a red title. The Class Details window shows all of the methods, properties, fields and correctly shows no events. However, there's an entry under each of methods, properties, fields and events that states where the name should be: "The type cannot be edited because the source code file contains an error." However, the source file builds with no errors or warnings. Anyone seen this? Any idea how to fix it?

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• Watir question regarding exist on a class for testing purposes.

  - by AJ

  I have a button on my page that changes depending on what radio button is clicked. The button has the same text on it with the same id, but different classes. How do I test if the two different buttons exist depending on the radio. <a id="submit" class="on" href="javascript:submit();">Submit</a> <a id="submit" class="off" href="javascript:submit();">Submit</a> How do i test if the second button appears instead of the first one. I used something like, browser.link(:text, 'Submit').exist? but this doesn't work cause it will return true no matter what. thanks

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• jQuery: modify href attribute for first level list only

  - by bloggerious

  I'm a noob in jQuery and have stuck at this. I have the following HTML code output from a PHP page: <ul class="cats"> <li><span><a href="cant_post_link_yet1">Lifestyle</a></span></li> <li><span><a href="cant_post_link_yet2">Entertainment</a></span></li> <li class="has_child"> <span><a href="cant_post_link_yet3">Technology</a></span> <ul class="subcats"> <li><span><a href="cant_post_link_yet4">Gadgets</a></span></li> <li><span><a href="cant_post_link_yet5">Hardware</a></span></li> </ul> </li> <li><span><a href="cant_post_link_yetsports">Sports</a></span></li> <li class="has_child"> <span><a href="cant_post_link_yet6">Design</a></span> <ul class="subcats"> <li class="has_child"> <span><a href="cant_post_link_yet7">Web Design</a></span> <ul class="subcat"> <li><span><a href="cant_post_link_yet8">Adobe Photoshop</a></span></li> </ul> </li> <li><span><a href="cant_post_link_yet9">Graphics and Print</a></span></li> </ul> </li> What's the correct jQuery code so that I can modify the href attribute for the first-level list only? Basically, I want to change the href of Technology and Design to be "#" but will not change the href of Web Design which is already on second-level list. More Info: In the code above, if list has subcategories, then it has the class has_child, whether it's on first-level or not. So I want only the first-level list which has class has_child to be modified the href to "#" I can't alter output anymore because it's in the PHP code. Any help is greatly appreciated.

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• How can I create a new class instance from a class within a (static) class?

  - by Mervin

  I'm new to Java (have experience with C#), This is what i want to do: public final class MyClass { public class MyRelatedClass { ... } } public class OtherRandomClass { public void DoStuff() { MyRelatedClass data = new MyClass.MyRelatedClass(); } } which gives this error in Eclipse: "No enclosing instance of type BitmapEffects is accessible. Must qualify the allocation with an enclosing instance of type BitmapEffects (e.g. x.new A() where x is an instance of BitmapEffects)." this is possible in C# with static classes , how should it be done here?

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• C++ method declaration, class definition problem

  - by John Fra.

  I have 2 classes: A and B. Some methods of class A need to use class B and the opposite(class B has methods that need to use class A). So I have: class A; class B { method1(A a) { } } class A { method1(B b) { } void foo() { } } and everything works fine. But when I try to call foo() of class A from B::method1 like this: class B { method1(A a) { a.foo(); } } I get as result compile errors of forward declaration and use of incomplete type. But why is this happening? (I have declared class A before using it?)

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• Howto write a class where a property can be accessed without naming it.

  - by SchlaWiener

  I have a (dump) question regarding VB/C# I often use third party classes where I can access a child object with only specifying the id or key. Example: Instead of writing: DataRow row = GetAPopulatedDataRowSomeWhere(); Object result = row.Items[1]; // DataRow has no Items property Object result = row.Items["colName"]; // Also not possible I use this code to access the members: DataRow row = GetAPopulatedDataRowSomeWhere(); Object result = row[1]; Object result = row["colName"]; Can someone tell me how a class has to look like to support this syntax? My own class has a Dictionary that I want to access this way. MyClass["key"]; // <- that's what I want MyClass.SubItems["key"]; // <- that's how I use it now

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• Should I use Enumeration or Class stereotype in UML to represent a type directory table?

  - by Ivan

  Let's take 2 UML class model entities: One represents an actual Order and another represents an Orede Type. Any Order corresponds to one Type. A 2-way-naviglabe many Orders to one Type relation is meant. Order Type instances are, for example, "Request availability", "Request price", "Preorder", "Buy", "Cancel", "Request support", etc. Order Types are to be addable and editable in the resulting application. Should I model Order Type as Class or as Enumeration? From the data perspective I can't see the difference actually.

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• PHP 5.3: Late static binding doesn't work for properties when defined in parent class while missing in child class

  - by DavidPesta

  Take a look at this example, and notice the outputs indicated. <?php class Mommy { protected static $_data = "Mommy Data"; public static function init( $data ) { static::$_data = $data; } public static function showData() { echo static::$_data . "<br>"; } } class Brother extends Mommy { } class Sister extends Mommy { } Brother::init( "Brother Data" ); Sister::init( "Sister Data" ); Brother::showData(); // Outputs: Sister Data Sister::showData(); // Outputs: Sister Data ?> My understanding was that using the static keyword would refer to the child class, but apparently it magically applies to the parent class whenever it is missing from the child class. (This is kind of a dangerous behavior for PHP, more on that explained below.) I have the following two things in mind for why I want to do this: I don't want the redundancy of defining all of the properties in all of the child classes. I want properties to be defined as defaults in the parent class and I want the child class definition to be able to override these properties wherever needed. The child class needs to exclude properties whenever the defaults are intended, which is why I don't define the properties in the child classes in the above example. However, if we are wanting to override a property at runtime (via the init method), it will override it for the parent class! From that point forward, child classes initialized earlier (as in the case of Brother) unexpectedly change on you. Apparently this is a result of child classes not having their own copy of the static property whenever it isn't explicitly defined inside of the child class--but instead of throwing an error it switches behavior of static to access the parent. Therefore, is there some way that the parent class could dynamically create a property that belongs to the child class without it appearing inside of the child class definition? That way the child class could have its own copy of the static property and the static keyword can refer to it properly, and it can be written to take into account parent property defaults. Or is there some other solution, good, bad, or ugly?

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• What happens to a class in PHP once its been instantiated?

  - by Caylem

  Hi I'm just playing around with some PHP and was wondering what happens when an object from a class is created within another PHP script? I assume once its created and been processed their is no way of then going back and 'playing' around with it from another script? The idea is i'm trying to create a kind of deck of cards using a card class, each card has specific data that is added to each individual object to make it unique, suit, value etc. Once its created i need to be able to go back to specific cards to use them. In java i'd have an arraylist of card objects, i'm not sure how to approach the same area in PHP. Thanks.

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• Pass Session data to a Class Library without using a bunch of constructors?

  - by sah302

  Hi all, I've got my application here where literally every object has a lastUpdatedBy property. The information I put into here is the person's username, which is retrieved from the session("username") variable. How can I pass this data to my DAL in the class library? At first I was just passing in the value into each method, but this is ridiculous I thought, there should be no reason to do that every time a method is called. Then I thought well if I just put it in a constructor for each of the DAL related classes, that will make it even easier. However, even still on any given page, I've got a plethora of New() declarations, for which every single line I need to pass in the session username casted as a string. Is there an even still more efficient way of doing this so that I could only declare this in one place, and everything will know what it is and I can pass it to classes in a class library?

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• jQuery script to move an attribute of matched element to their children

  - by UserControl

  I have a set of anchors like <a class="lb" href="#">text</a> <a class="lb" href="#" style="width:200px">text</a> <a class="lb" href="#" style="color: reen; width:200px">text</a> that needs to be transformed to the following: <a class="lb" href="#"><span>text</span></a> <a class="lb" href="#"><span style="width:200px">text</span></a> <a class="lb" href="#" style="color:green"><span style="width:200px">text</span></a> I have no problem creating child span but don't know how to move parent's width styling.

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• jQuery script to move an attribute of matched elements to their children

  - by UserControl

  I have a set of anchors like <a class="lb" href="#">text</a> <a class="lb" href="#" style="width:200px">text</a> <a class="lb" href="#" style="color: reen; width:200px">text</a> that needs to be transformed to the following: <a class="lb" href="#"><span>text</span></a> <a class="lb" href="#"><span style="width:200px">text</span></a> <a class="lb" href="#" style="color:green"><span style="width:200px">text</span></a> I have no problem creating child span but don't know how to move parent's width styling.

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• In java can i have more than one class/object in a file?

  - by David

  So the way i've been told to do things is you have your file and the file name is Classname.java and then the code is something like this: class ClassName { SOME METHODS main {} } and then thats all. I'd like to have two objects defined and used within the same .java file. (i don't want to have to put the other class in a difernt file just because i'd like to send this to someone and i want to avoid hasstle of atatching multiple files to an email [the lazy do make good programers though if you think about it]) is it possible to do this? do i have to do anything special and if so what? what are some mistakes i'm likely to make or that you have made in the past when doing this?

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