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  • How can I reuse a base class function in a derived class

    - by Armen Ablak
    Let's say we have these four classes: BinaryTree, SplayTree (which is a sub-class of BinaryTree), BinaryNode and SplayNode (which is a sub-class of BinaryNode). In class BinaryTree I have 2 Find functions, like this bool Find(const T &) const; virtual Node<T> * Find(const T &, Node<T> *) const; and in SplayTree I would like to reuse the second one, because it works in the same way (for example) as in SplayTree, the only thing different is the return type, which is SplayNode. I thought it might be enough if I use this line in SplayTree.cpp using BinaryTree::Find; but it isn't. So, how can I do this?

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  • Templates --> How to decipher, decide if necessary and create?

    - by ML
    Hi All, I have a few classes in a project that I inherited that are really old, last I knew they compiled with CodeWarrior 8. I am not in XCode 3.2 Here is an example of what I struggle with: template <class registeredObject> typename std::vector<registeredObject>::iterator FxRegistry<registeredObject>::begin(void) { return mRegistryList.begin(); } The errors are: no 'typename std::vector<registeredObject, std::allocator<_CharT> >::iterator FxRegistry<registeredObject>::begin()' member function declared in class 'FxRegistry<registeredObject>' template definition of non-template 'typename std::vector<registeredObject, std::allocator<_CharT> >::iterator FxRegistry<registeredObject>::begin()' How do I decide how to solve these and where do I start looking?

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  • Problem overridding virtual function

    - by William
    Okay, I'm writing a game that has a vector of a pairent class (enemy) that s going to be filled with children classes (goomba, koopa, boss1) and I need to make it so when I call update it calls the childclasses respective update. I have managed to create a example of my problem. #include <stdio.h> class A{ public: virtual void print(){printf("Hello from A");} }; class B : public A{ public: void print(){printf("Hello from B");} }; int main(){ A ab = B(); ab.print(); while(true){} } Output wanted: "Hello from B" Output got: "Hello from A" How do I get it to call B's print function?

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  • Access Relationship Table in Grails

    - by WaZ
    Hi, I have the following domains classes: class Posts{ String Name String Country static hasMany = [tags:Tags] static constraints = { } } class Tags{ String Name static belongsTo = Posts static hasMany = [posts:Posts] static constraints = { } String toString() { "${TypeName}" } } Grails creates an another table in the database i.e. Posts_Tags. My requirement is: E.g. 1 post has 3 tags. So, in the Posts_Tags table there are 3 rows. How can I access the table Posts_Tags directly in my code so that I can manipulate the data or add some more fields to it.

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  • Using multiple databases within one application

    - by Alex
    I have a web application made for several groups of people not connected with each other. Instead of using one database for all of them, I'm thinking about making separate databases. This will improve the speed of the queries and make me free from checking to what group the user belongs. But since I'm working with LINQ to SQL, my classes are explicitly connected with the databases, so I will have to make separate DataContexts for all of the databases. So how can I solve this problem? Or should I just not bother and use one database only?

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  • How can I persist a large Perl object for re-use between runs?

    - by Alnitak
    I've got a large XML file, which takes over 40 seconds to parse with XML::Simple. I'd like to be able to cache the resulting parsed object so that on the next run I can just retrieve the parsed object and not reparse the whole file. I've looked at using Data::Dumper but the documentation is a bit lacking on how to store and retrieve its output from disk files. Other classes I've looked at (e.g. Cache::Cache appear designed for storage of many small objects, not a single large one. Can anyone recommend a module designed for this? EDIT. The XML file is ftp://ftp.rfc-editor.org/in-notes/rfc-index.xml On my Mac Pro benchmark figures for reading the entire file with XML::Simple vs Storable are: s/iter test1 test2 test1 47.8 -- -100% test2 0.148 32185% --

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  • How do I create a point system in a Rails app that assigns points to users and non-authenticated-use

    - by codyvbrown
    I'm building a question and answer application on top of twitter and I'm hitting some snags because I'm inevitably dealing with two classes of users: authenticated and non-authenticated. The site enable users to give points to other users, who may or may not be authenticated, and I want to create a site-wide point system where the application stores and displays this information on their profile. I want to save this point data to the user because that would be faster and more efficient but non-authenticated users aren't in our system, we only have the twitter handle. So instead we display the points in our system like this: @points = point.all( :select => "tag, count(*) AS count", # Return tag and count :group => 'tag', # Group by the tag :order => "2 desc", :conditions => {:twitter_handle => params[:username]}) Is there a better way to do this? Is there a better way to associate data with non-authenticated users?

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  • Managing Data Prefetching and Dependencies with .NET Typed Datasets

    - by Derek Morrison
    I'm using .NET typed datasets on a project, and I often get into situations where I prefetch data from several tables into a dataset and then pass that dataset to several methods for processing. It seems cleaner to let each method decide exactly which data it needs and then load the data itself. However, several of the methods work with the same data, and I want the performance benefit of loading data in the beginning only once. My problem is that I don't know of a good way or pattern to use for managing dependencies (I want to be sure I load all the data that I'm going to need for each class/method that will use the dataset). Currently, I just end up looking through the code for the various classes that will use the dataset to make sure I'm loading everything appropriately. What are good approaches or patterns to use in this situation? Am I doing something fundamentally wrong? Although I'm using typed datasets, this seems like it would be a common situation where prefetching data is used. Thanks!

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  • Check for state change in objects using serialization?

    - by sev7n
    I have a form that is bind to an object, and when the user trying to leave the form, I want to warn them if anything on the form has been changed, and prompt them to save. My question is, is there any way to achieve this without implementing IComparar for all my classes in the binded object? I was thinking if there is a way I can serialize my object when loading the form, and do a simple comparison against the change object that also get serialized. Something like a string comparison. Hope that make sense, Thanks

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  • How to make Event visible?

    - by eflles
    Inside a Silverlight library project I have a public event, which is not visible for other classes. How can I make the event visible? When I try the following code, I can not locate the event in the "ReceivingClass". .dll - file: Public Class MyClass Public Event MyEvent(ByVal sender As Object, ByVal e As EventArgs) Public Sub OnStart() RaiseEvent MyEvent(Me, new EventArgs) End Sub End Class Silverlight app: Imports MyClass Public Class ReceivingClass Public Sub New() Dim myClass As new MyClass AddHandler myClass.MyEvent, AddressOf Me.EventHandler End Sub Private Sub EventHandler(ByVal sender As Object, ByVal e As EventArgs) 'Handle Event End Sub End Class

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  • C++ memory management of reference types

    - by Russel
    Hello, I'm still a fairly novice programmer and I have a question about c++ memory management with refence types. First of all, my understanding of reference types: A pointer is put on the stack and the actual data that the pointer points to is created and placed on the heap. Standard arrays and user defined classes are refence types. Is this correct? Second, my main question is do c and c++'s memory management mechanisms (malloc, free and new, delete) always handle this properly and free the memory that a class or array is pointing to? Does everything still work if those pointers get reassigned somehow to other objects of the same size/type on the heap? What if a class has a pointer member that points to another object? I am assuming that delete/freeing the class object doesn't free what it's member pointer points to, is that correct? Thanks all! -R

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  • QWebPage. How to handle failed request.

    - by user453482
    I want to handle failed requests (for example, with http 404 error code in reply), display my own "notfound.html" page in QWebView. But there is no simple way to handle replies with QWebView/QWebPage classes. As I see in Arora browser, for such requests uses next mechanism: QWebPage::setForwardUnsupportedContent(true), QWebPage::unsupportedContent signal and appropriate slot where you can handle qnetworkreply manually. But I cannot understand how it works, because unsupportedContent throws only when QWebPage cannot handle request scheme (like abrakadra://, ftp://, etc) or if reply consists of special header Content-Disposition: attachment. May be anybody know something about this ?

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  • Simplest way to extend doctrine for MVC Models

    - by RobertPitt
    Im developing my own framework that uses namespaces. Doctrine is already integrated into my auto loading system and im now at the stage where ill be creating the model system for my application Usually i would create a simple model like so: namespace Application\Models; class Users extends \Framework\Models\Database{} which would inherit all the default database model methods, But with Doctrine im still learning how it all works, as its not just a simple DBAL. I need to understand whats the part of doctrine my classes would extend where i can do the following: namespace Application\Models; class Users Extends Doctrine\Something\Table { public $__table_name = "users"; } And thus within the controller i would be able to do the following: public function Display($uid) { $User = $this->Model->Users->findOne(array("id" => (int)$id)); } Anyone help me get my head around this ?

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  • Summary count for Python logging

    - by Craig McQueen
    At the end of my Python program, I'd like to be able to get a summary of the number of items logged through the standard logging module. I'd specifically like to be able to get a count for each specified name (and possibly its children). E.g. if I have: input_logger = getLogger('input') input_logger.debug("got input1") input_logger.debug("got input2") input_logger.debug("got input3") network_input_logger = getLogger('input.network') network_input_logger.debug("got network input1") network_input_logger.debug("got network input2") getLogger('output') output_logger.debug("sent output1") Then at the end I'd like to get a summary such as: input: 5 input.network: 2 output: 1 Perhaps by calling a getcount() method for a logger or a handler. What would be a good way to achieve this? I imagine it would involve a sub-class of one of the logging classes, but I'm not sure which one would be best.

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  • Best way to test instance methods without running __init__

    - by KenFar
    I've got a simple class that gets most of its arguments via init, which also runs a variety of private methods that do most of the work. Output is available either through access to object variables or public methods. Here's the problem - I'd like my unittest framework to directly call the private methods called by init with different data - without going through init. What's the best way to do this? So far, I've been refactoring these classes so that init does less and data is passed in separately. This makes testing easy, but I think the usability of the class suffers a little. EDIT: Example solution based on Ignacio's answer: import types class C(object): def __init__(self, number): new_number = self._foo(number) self._bar(new_number) def _foo(self, number): return number * 2 def _bar(self, number): print number * 10 #--- normal execution - should print 160: ------- MyC = C(8) #--- testing execution - should print 80 -------- MyC = object.__new__(C) MyC._bar(8)

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  • how to import Java class with Python using Eclipse?

    - by JChao
    Hi, I'm trying to write Jython where the Python file imports classes from Java I'm using Eclipse with PyDev. My Python code looks like: from eclipsejavatest import eclipseJavaTest from eclipsejavatest import JavaClass class eclipsePyPrint(eclipseJavaTest): def eclipsepyMain(self): print "python main method" eclipseJavaTest.printerCount(4) print eclipseJavaTest.gotoPython() eclipseJavaTest.printerSentence() samplepyClass = JavaClass("Jython plain") samplepyClass.setName("jython fancy") print samplepyClass.getName() but I'm getting the error ImportError: No module named eclipsejavatest The Python project references the Java project. I've tried exporting the Java project and adding the .jar to the Jython Class Path for the Python project. I'm not sure what to do to get this to work.

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  • Running a method after the constructor of any derived class

    - by Alexey Romanov
    Let's say I have a Java class abstract class Base { abstract void init(); ... } and I know every derived class will have to call init() after it's constructed. I could, of course, simply call it in the derived classes' constructors: class Derived1 extends Base { Derived1() { ... init(); } } class Derived2 extends Base { Derived2() { ... init(); } } but this breaks "don't repeat yourself" principle rather badly (and there are going to be many subclasses of Base). Of course, the init() call can't go into the Base() constructor, since it would be executed too early. Any ideas how to bypass this problem? I would be quite happy to see a Scala solution, too.

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  • Is there any Android XML documentation?

    - by Eddified
    Is there any sort of xml reference? I found this which turned out to be invaluable for me http://groups.google.com/group/android-developers/msg/d334017d72909c79 but I can't figure out how I was supposed to know how to do that, had I not found that post. I know that the api reference has xml attributes listed for many of the classes... but what about xml tags? Where is it documented that I could build a shape using , , tags? I'd really like to know where I can find such documentation.

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  • PHP: How to Pass child class __construct() arguments to parent::__construct() ?

    - by none
    I have a class in PHP like so: class ParentClass { function __construct($arg) { // Initialize a/some variable(s) based on $arg } } It has a child class, as such: class ChildClass extends ParentClass { function __construct($arg) { // Let the parent handle construction. parent::__construct($arg); } } What if, for some reason, the ParentClass needs to change to take more than one optional argument, which I would like my Child class to provide "just in case"? Unless I re-code the ChildClass, it will only ever take the one argument to the constructor, and will only ever pass that one argument. Is this so rare or such a bad practice that the usual case is that a ChildClass wouldn't need to be inheriting from a ParentClass that takes different arguments? Essentially, I've seen in Python where you can pass a potentially unknown number of arguments to a function via somefunction(*args) where 'args' is an array/iterable of some kind. Does something like this exist in PHP? Or should I refactor these classes before proceeding?

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  • Java Swing architecture for flipping through JPane based views

    - by imhotep
    Hi all, I have done a couple of simple swing based apps with static layout, but now I've run into a problem while trying to create an app containing multiple views which are changed by pressing appropriate navigational button. You could compare the idea to a website so that every view has buttons to access certain other views but this would work inside a single JFrame. I've found that maybe CardLayout (Cardlayout example) might be appropriate solution for this kind of structure, but I'm unable to figure out a way to switch the views from the buttons which are inside of the JPanes that I've implemented in their separate classes, Of course one way would be to instantiate everything in the parent class like in the small java tutorial example, but this isn't quite clean nor modular for multiple views, isn't it. How can this be implemented so that I can access the view switching method?

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  • Is it weird or strange to make multiple WCF Calls to build a ViewModel before presenting it?

    - by Nate Bross
    Am I doing something wrong if I need code like this in a Controller? Should I be doing something differently? public ActionResult Details(int id) { var svc = new ServiceClient(); var model = new MyViewModel(); model.ObjectA = svc.GetObjectA(id); model.ObjectB = svc.GetObjectB(id); model.ObjectC = svc.GetObjectC(id); return View(model); } The reason I ask, is because I've got Linq-To-Sql on the back end and a WCF Service which exposes functionality through a set of DTOs which are NOT the Linq-To-Sql generated classes and thus do not have the parent/child properties; but in the detail view, I would like to see some of the parent/child data.

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  • How binding each column to other data source..

    - by liran
    hello, i have datagridview and Object data source : public class Data { public general general { get; set; } public Person Person { get; set; } } public class general { public int Id { get; set; } public int Name { get; set; } } public class Person { public int Tag { get; set;} } } i want to bind first column to general.id and second to person.Tag, how i do this, its is possible to bind each column to other dataSource without add any code in data, person or general classes. maybe need to add column manually? Thanks

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  • Interview question: difference between object and object-oriented languages.

    - by Bar
    My friend was asked the following question: what's the difference between object language and object-oriented language? It's a little unintelligible question. What does term «object language» correspond to? Does that mean «pure» object-oriented language, like the Wikipedia article says: Languages called "pure" OO languages, because everything in them is treated consistently as an object, from primitives such as characters and punctuation, all the way up to whole classes, prototypes, blocks, modules, etc. They were designed specifically to facilitate, even enforce, OO methods. Examples: Smalltalk, Eiffel, Ruby, JADE, VB.NET.

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  • JRI Fatal Error on Ubuntu

    - by Peter Jackson
    I have successfully installed JRI and rJava on Windows 7. I am now trying to get it to work on Ubuntu with 64bit OS. I can make rJava calls from within R but getting JRI to work is more difficult. I am running NetBeans 7.1.2 and I have followed various tricks in setting R_HOME and java.library.path to enable all the classes to be loaded. That is, I am past the error messages such as "jri library not found" and "R_HOME not set". From my java code,I can see that R_HOME = /usr/lib64/R. The error message I get now is Fatal error: you must specify '--save', '--no-save' or '--vanilla' This happens when Rengine is first called: Rengine r = new Rengine(args,false,null); This appears to be an error message from R; it seems to be expecting a command line argument. I haven't seen any posting with this error message. Any ideas? Thanks, Peter

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  • Rails + simple role system through associative table

    - by user202411
    So I have the Ninja model which has many Hovercrafts through ninja_hovercrafts (which stores the ninja_id and the hovercraft_id). It is of my understanding that this kind of arrangement should be set in a way that the associative table stores only enough information to bind two different classes. But I'd like to use the associative table to work as a very streamlined authorization hub on my application. So i'd also like this table to inform my system if this binding makes the ninja the pilot or co-pilot of a given hovercraft, through a "role" field in the table. My questions are: Is this ugly? Is this normal? Are there methods built into rails that would help me to automagically create Ninjas and Hovercrafts associations WITH the role? For exemple, could I have a nested form to create both ninjas and hcs in a way that the role field in ninjas_hovercrafts would be also filled? If managing my application roles this way isn't a good idea, whats the non-resource heavy alternative (my app is being designed trying to avoid scalability problems such as excessive joins, includes, etc) thank you

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