Suppose I have a class A. And B and C are child of A. Class A has a generic algorithm for sorting arrays of type A, so that I could use it for B and C without writing again the algorithm for each. In the algorithm, sometimes I have to swap. The problem is that I can only see the objects as type A, and if I do: A aux = array[i] array[...
I have a simple inheritance heirarchy with MyType2 inheriting from MyType1. I have an instance of MyType1, arg, passed in as an argument to a method. If arg is an instance of MyType2, then I'd like to perform some logic, transforming the instance. My code looks something like the code below. Having to create a new local variable b feel...
Ok, I have a relationship between People, Users and Employees such that All Employees are Users and all Users are People. Person is an abstract class that User is derived from and Employee is derived from that. Now... I have an EmployeesController class and the create method looks like this: def create @employee = Employee.new(params...
Okay, I'm pretty inexperienced as a programmer, let alone in C++, so bear with me here. What I wanted to do was to have a container class hold a parent class pointer and then use polymorphism to store a child class object. The thing is that I want to call one of the child class's functions through the parent class pointer. Here's a sort ...
I was wondering how to do this, consider the following classes public class Fruit { public string Name { get; set; } public Color Color { get; set; } } public class Apple : Fruit { public Apple() { } } How can I instantiate a new fruit but upcast to Apple, is there a way to instantiate a bunch of Fruit and make th...
Given the following situation (UML below), If Y has the method: public void PrintWs(); and X has: ArrayList <P> myPs = new ArrayList(); Y y = new Y(); Z z = new Z(); myPs.add(y); myPs.add(z); How do I loop through each myPs object and call all Ys PrintWs (without using instanceof)? http://starbucks.mirror.waffleimages.com/files/...
Hi, this is my first question here :) I know that I should not check for object type but instead use dynamic_cast, but that would not solve my problem. I have class called Extension and interfaces called IExtendable and IInitializable, IUpdatable, ILoadable, IDrawable (the last four are basicly the same). If Extension implements IExten...
I'm working on a homework assignment (a project), for which one criterion is that I must make use of polymorphism in a way which noticeably improves the overall quality or functionality of my code. I made a Hash Table which looks like this: public class HashTable<E extends Hashable>{ ... } where Hashable is an interface I made th...
Hi There, I am fairly new to OOP and wondered if you could provide some help on the best solution to the following. public class GenericClass { private List<GenericListItem> _listItems; } public class SpecificClass : GenericClass { // I'd like to change the listItems specialisation to SpecificListItem (inherits from GenericLis...
I'm attempting to write a policy-based host class (i.e., a class that inherits from its template class), with a twist, where the policy class is also templated by the host class, so that it can access its types. One example where this might be useful is where a policy (used like a mixin, really), augments the host class with a polymorphi...
The following code, prints out Derived Base Base But I need every Derived object put into User::items, call its own print function, but not the base class one. Can I achieve that without using pointers? If it is not possible, how should I write the function that deletes User::items one by one and frees memory, so that there should not...
Hi, I'm trying to grasp higher-order-polymophism in scala by implementing a very basic interface that describes a monad but I come across a problem that I don't really understand. I implemented the same with C++ and the code looks like this: #include <iostream> template <typename T> class Value { private: T value; public: Value(c...
how can i access state varibale of class keyboard with object of class kalaplayer /** * An abstract class representing a player in Kala. Extend this class * to make your own players (e.g. human players entering moves at the keyboard * or computer players with programmed strategies for making moves). ...
Take the following code class A { }; class B : public A { }; class C : public A { int x; }; int main (int argc, char** argv) { A* b = new B(); A* c = new C(); //in both cases, only ~A() is called, not ~B() or ~C() delete b; //is this ok? delete c; //does this line leak memory? return 0; } when calling delete on...
Hello Everyone, I'm trying to implement a Polymorphic Queue. Here is my trial: QQueue <Request *> requests; while(...) { QString line = QString::fromUtf8(client->readLine()).trimmed(); if(...)){ Request *request=new Request(); request->tcpMessage=line.toUtf8(); ...
Hey guys, I wanted some help with trying to implement a simple polymorphic relationship using Entity Framework. An example of a relationship I would like to implement: Comment table ItemType ('Video', 'User') ItemID Body Video has many Comments User has many Comments No idea the best way to do this, I c...
Hi, I have a question about a problem I'm struggling with. Hope you can bear with me. Imagine I have an Object class representing the base class of a hierarchy of physical objects. Later I inherit from it to create an Object1D, Object2D and Object3D classes. Each of these derived classes will have some specific methods and attributes....
I was wondering if anyone could tell me if this kind of behaviour is possible in C# 4.0 I have an object hierarchy I'd like to keep strongly typed. Something like this class ItemBase {} class ItemType<T> where T : ItemBase { T Base { get; set; } } class EquipmentBase : ItemBase {} class EquipmentType : ItemType<EquipmentBase> {}...
Below program contains two show() functions in parent and child classes, but first show() function takes FLOAT argument and second show() function takes INT argument. .If I call show(10.1234) function by passing float argument, it should call class A's show(float a) function , but it calls class B's show(int b). #include<iostream> usin...
Hi, all. I'm pretty new to C++, and I'm writing a small library (mostly for my own projects) in C++. In the process of designing a type hierarchy, I've run into the problem of defining the assignment operator. I've taken the basic approach that was eventually reached in this article, which is that for every class MyClass in a hierarchy ...