inheritance

constructors and inheritance in JS

Hi all, This is about "inheritance" in JavaScript. Supose I create a constructor Bird(), and another called Parrot() which I make to "inherit" the props of Bird by asigning an instance of it to Parrot's prototype, like the following code shows: function Bird() { this.fly = function(){}; } function Parrot() { this.talk = funct...

How can I make datagridview can only select the cells in the same column at a time?

I am using winforms to develop my application. And I set my datagridview control's selectionmode to "CellSelect", and this allow the user to select as many cells as he want which spread over several columns; but I want to constraint my user can only select cells in single column at a time, and there isn't any such kind of selectionmode ...

C++ Implicit Conversion Operators

I'm trying to find a nice inheritance solution in C++. I have a Rectangle class and a Square class. The Square class can't publicly inherit from Rectangle, because it cannot completely fulfill the rectangle's requirements. For example, a Rectangle can have it's width and height each set separately, and this of course is impossible with ...

django class with an array of "parent" foreignkeys issue

Let's say I have a class called Fruit with child classes of the different kinds of Fruit with their own specific attributes, and I want to collect them in a FruitBasket: class Fruit(models.Model):     type = models.CharField(max_length=120,default='banana',choices=FRUIT_TYPES)     ... class Banana(Fruit):     """banana (fruit type)""" ...

How do I override a parent class's functions in python?

I have a private method def __pickSide(self): in a parent class that I would like to override in the child class. However, the child class still calls the inherited def __pickSide(self):. How can I override the function? The child class's function name is exactly the same as the parent's function name. ...

Why aren't return types considered in Java method overloads?

Why return type of a method is not considered in method overloading ? Can somebody explain , how compiler checks for overloaded methods ? ...

C# - implementing GetEnumerator() for a collection inherited from List<string>

Hi, I am trying to implement FilePathCollection. Its items would be simple file names (without a path - such as "image.jpg"). Once the collection is used via foreach cycle, it should return the full path created by concatenating with "baseDirectory". How can I do that? public class FilePathCollection : List<string> { string baseDi...

Python: Inheritance of a class attribute (list)

Hi everyone, inheriting a class attribute from a super class and later changing the value for the subclass works fine: class Unit(object): value = 10 class Archer(Unit): pass print Unit.value print Archer.value Archer.value = 5 print Unit.value print Archer.value leads to the output: 10 10 10 5 which is just fine: Archer ...

Why can't sub-packages see package private classes?

Okay so, I have this project structure: package A.B class SuperClass (this class is marked package private) package A.B.C class SubClass (inherits from super class) I'd rather not make SuperClass publicly visible... It is really just a utility class for this specific project (A.B). It seems to me that SubClass should be able ...

Tricky model inheritance - Django

Hi folks, I think this is a bit tricky, at least for me. :) So I have 4 models Person, Singer, Bassist and Ninja. Singer, Bassist and Ninja inherit from Person. The problem is that each Person can be any of its subclasses. e.g. A person can be a Singer and a Ninja. Another Person can be a Bassist and a Ninja. Another one can be a...

Mutable class as a child of an immutable class

I want to have immutable Java objects like this (strongly simplyfied): class Immutable { protected String name; public Immutable(String name) { this.name = name; } public String getName() { return name; } } In some cases the object should not only be readable but mutable, so I could add mutabili...

XML Schema for a .NET type that inherits and implements

Hi, Please consider the following three .NET types: I have an interface, an abstract class, and a concrete class. My question is how to write the XML Schema to include the properties from the interface and from the abstract class. public interface IStartable { bool RequiresKey { get; set; } void Start(object key); } public a...

Why does a function that takes IEnumerable<interface> not accept IEnumerable<class>?

Say, for instance, I have a class: public class MyFoo : IMyBar { ... } Then, I would want to use the following code: List<MyFoo> classList = new List<MyFoo>(); classList.Add(new MyFoo(1)); classList.Add(new MyFoo(2)); classList.Add(new MyFoo(3)); List<IMyBar> interfaceList = new List<IMyBar>(classList); But this produces the e...

Implementing IDisposable on a subclass when the parent also implements IDisposable

I have a parent and child class that both need to implement IDisposable. Where should virtual (and base.Dispose()?) calls come into play? When I just override the Dispose(bool disposing) call, it feels really strange stating that I implement IDisposable without having an explicit Dispose() function (just utilizing the inherited one), b...

Protect CSS-layout for overlaying div like addthis.com

I have an overlaying div (much like addthis.com) that I want to protect from inheriting styles. I have looked at reset-css files such as Blueprint but this tends to screw up the parent styles as well. For instance: User has div { border-right:1px solid red; } This is appended to all divs on the page, including my overlay. Of course I ...

How to prevent Visual Studio setting my default font sizes in an inherited control

I have a base class for all my textboxes and I want to set the default font in that class. So I started with this: public partial class MyTextBox : TextBox { public WmlTextBox() { InitializeComponent(); //Font for the whole application can be altered in the Appearance class Font = new Appearance().TextBoxFo...

C# Hiding, overriding and calling function from base class.

I'm learning C# and I encountered the following problem. I have two classes: base and derived: class MyBase { public void MyMethod() { Console.WriteLine("MyBase::MyMethod()"); } } class MyDerived: MyBase { public void MyMethod() { Console.WriteLine("MyDerived::MyMethod()"); } } For now, withou...

ASP.NET Model Binder and base type

My model inherits from an interface: public interface IGrid { ISearchExpression Search { get; set; } . . } public interface ISearchExpression { IRelationPredicateBucket Get(); } The model: public class Project : IGrid { public ISearchExpression Search { get; set; } public Project() { t...

Should I use a metaclass, class decorator, or override the __new__ method?

Here is my problem. I want the following class to have a bunch of property attributes. I could either write them all out like foo and bar, or based on some other examples I've seen, it looks like I could use a class decorator, a metaclass, or override the __new__ method to set the properties automagically. I'm just not sure what the "...

Why can't I override and new a Property (C#) at the same time?

According to this question it seems like you can do this for Methods. What I want to know is why it doesn't work when I try it with properties. public class Foo { public virtual object Value { get; set; } } public class Foo<T> : Foo { public override object Value { get { r...