inheritance

Does Qt support virtual pure slots ?

Hi, My GUI project in Qt has a lot of "configuration pages" classes which all inherit directly from QWidget. Recently, I realized that all these classes share 2 commons slots (loadSettings() and saveSettings()). Regarding this, I have two questions: Does it make sense to write a intermediate base abstract class (lets name it BaseCon...

Interface and base class mix, the right way to implement this

I have some user controls which I want to specify properties and methods for. They inherit from a base class, because they all have properties such as "Foo" and "Bar", and the reason I used a base class is so that I dont have to manually implement all of these properties in each derived class. However, I want to have a method that is o...

Python Decorators and inheritance

Help a guy out. Can't seem to get a decorator to work with inheritance. Broke it down to the simplest little example in my scratch workspace. Still can't seem to get it working. class bar(object): def __init__(self): self.val = 4 def setVal(self,x): self.val = x def decor(self, func): def increment...

django aggregation with objects

model: class Product(models.Model): name = models.CharField(max_length = 128) (...) def __unicode__(self): return self.name class Receipt(models.Model): name = models.CharField(max_length=128) (...) components = models.ManyToManyField(Product, through='ReceiptComponent') def __unicode__(self): return self.nam...

How to get the DiscriminatorValue at run time

We have the following classes @Entity @Inheritance(strategy = InheritanceType.SINGLE_TABLE) // optional annotation as this is default @DiscriminatorColumn(name = "apType", discriminatorType = DiscriminatorType.STRING, length = 255) @DiscriminatorValue("AP") public class ApplicationProcess { } And this @Entity @DiscriminatorValue("AP...

foreach inherited (sub-class) object in a super-class list

I have a super-class named "ClassA" and two sub-classes "Class1" and "Class2". I have a list containing objects of "Class1" and "Class2", that list is of type "ClassA". I want to loop through only the "Class1" objects in the list by doing something like List<ClassA> AList = new List<ClassA>; AList.Add(new Class1()); AList.Add(new Clas...

Inheriting a Base Form but Paste/Cut Commands Not Captured

I created a base form that has a specific size and an icon as a base for all forms created in my project (to be consistent in looks). The problem is, for some reason if I add a Text box to the Child form, I can no longer execute shortcuts like Copy (CTRL+C) etc into the Textbox. What should I do to handle this OTHER THAN writing code to...

Why does Java allow multiple inheritance from interfaces but not from abstract/concrete classes

Possible Duplicate: Why there is no multiple inheritance in Java, but implementing multiple interfaces is allowed Why Java allows multiple inheritance from interfaces but not from abstract or concrete classes ...

WPF Window Inheritance

I have an application that will run in two modes, each with very similar displays. The application is supposed to allow easy modification of a user interface. One of the features is that it has to display the user interface. Both of these windows look the same, just one has more menus than the other. I'd like to just create a base templ...

How to map inheritance with property returned other inheritance?

Hi I have abstract class Vehicle and two classes that derive from: Car and ForkLift. public abstract class Vehicle { public EngineBase Engine { get; set; } } public class Car : Vehicle { public GasEngine Engine { get; set; } } public class ForkLift : Vehicle { public ElectricEngine Engine { get; set; } } and Engine clas...

How to get the path of a derived class from an inherited method?

How to get the path of the current class, from an inherited method? I have the following: <?php // file: /parentDir/class.php class Parent { protected function getDir() { return dirname(__FILE__); } } ?> and <?php // file: /childDir/class.php class Child extends Parent { public function __constru...

Java generics question

So I have 3 classes. Abstract class A Class B extends class A independent Class C In class D that contains the main method, I create a list of instances of class B List<B> b = methodCall(); // the method returns a list of instances of class B Now in class C I have one method that is common to both A and B, and hence I don't wa...

Unable to find assembly, C#

So, here's the deal. I've got two ASP.NET applications, both of which use SQLServer Session State management. They also both use the same server. I've got a custom session class in an external DLL, which fully implements serialization, and which both applications have referenced. Each application, in turn, has a class which inherits from...

Class inheritance in PHP 5.2: Overriding static variable in extension class?

Hi, I need to bea be able to use a static variable set in a class that extends a base class... from the base class. Consider this: class Animal { public static $color = 'black'; public static function get_color() { return self::$color; } } class Dog extends Animal { public static $color = 'brown'; } echo...

C++ Multiple inheritance with interfaces?

Greetings all, I come from Java background and I am having difficulty with multiple inheritance. I have an interface called IView which has init() method.I want to derive a new class called PlaneViewer implementing above interface and extend another class. (QWidget). My implementation is as: IViwer.h (only Header file , no CPP file) ...

Entity Framework 4: Inheritance and Optimistic Concurrency

Hi guys, I'm using AdventureWorks 2008 R2 database and added the BusinessEntity and Person tables to my EDMX. Then I changed the model in which the Person table inherits from the BusinessEntity table. As you may know these two tables have ModifiedDate and rowguid columns so the Person class should not have these properties because it inh...

Writing for others

What are the main and most important rules (pros and cons) I have to apply when I write a class that will be inherited by third party. Thank you. ...

Constructor Overload Problem in C++ Inheritance

Here my code snippet: class Request { public: Request(void); ……….. } Request::Request(void) { qDebug()<<"Request: "<<"Hello World"; } class LoginRequest :public Request { public: LoginRequest(void); LoginRequest(QDomDocument); …………… } LoginRequest::LoginRequest(void) { qDebug()<<"LoginRequest: "<<"Hello World"; requestType=LOG...

improve javascript prototypal inheritance

I'm using a classical javascript prototypal inheritance, like this: function Foo() {} Naknek.prototype = { //Do something }; var Foo = window.Foo = new Foo(); I want to know how I can improve this and why I can't use this model: var Foo = window.Foo = new function() { }; Foo.prototype = { //Do something }; Why this code doesn't ...

Make Java parent class not part of the interface

(This is a hypothetical question for discussion, I have no actual problem). Say that I'm making an implementation of SortedSet by extending LinkedHashMap: class LinkedHashSortedMapThing extends LinkedHashMap implements SortedSet { ... } Now programmers who use this class may do LinkedHashMap x = new LinkedHashSortedMapThing(); Bu...