subclass

I want to subclass the built-in DropDownList in ASP.NET so that I can add functionality to it and use it in my pages. I tried doing this with a UserControl but found that it doesn't expose the internal DropDownList (logically, I guess). I've googled for the answer but can't find anything. I've come as far as writing the actual class, and it's possible to subclass from DropDownList but I'm unable to register the file in my ASP.NET page and use it in the source view. Maybe I'm missing some properties in my class? Any ideas? You want to extend DropDownList in a Custom Control... not in a

I want to implement a custom subclass of UIControl. It works beautifully except for one fatal problem that is making me spit teeth. Whenever I use sendActionsForControlEvents: to send an action message out, it omits to include a UIEvent. For example, if I link it to a method with the following signature: - (IBAction) controlTouched:(id)sender withEvent:(UIEvent *)event ... the event always comes back as nil! The problem seems to occur within sendActionsForControlEvents: Now, I need my IBAction to be able to determine the location of the touch. I usually do so by extracting the touches from the

What does the memory usage look like in Java when extending a base class. Do the child class contain an instance of the base class (with it's own overhead and all) or does it only have it's own overhead of 16 Bytes? class Foo { int x; } class Bar extends Foo { int y; } So, more specifically, what is the memory usage of an instance of Bar? Is it Foo (including overhead) + Bar(including overhead) or just Foo (excluding overhead + Bar(including overhead) There is no double overhead. Java will take the class, the superclasses, compute the space needed for all the fields, and allocate space needed

I realize that, strictly speaking, this is not subclassing the array type, but will this work in the way one might expect, or am I still going to run into some issues with .length and the like? Are there any drawbacks that I would not have if normal subclassing were an option? function Vector() { var vector = []; vector.sum = function() { sum = 0.0; for(i = 0; i < this.length; i++) { sum += this[i]; } return sum; } return vector; } v = Vector(); v.push(1); v.push(2); console.log(v.sum()); I'd wrap an array inside a proper vector type like this: window.Vector = function Vector() { this.data = [

Basically what the title says. I have been referring to Base objects as subobjects. Is that correct and would it also be correct that subobject == superclass object ? Which one is preferred? The subclass means the derived class and the subclass object means the derived class' object, right? The confusion for me is that subclass object != subobject . If any of this is right, anyway.. Thanks The C++ Standard has a clear definition of what a subobject is. That said, many people don't (precisely) use the language of the Standard when talking about C++. One popular example is the term object . From

I want to invoke a protected method of another instance from within a subclass of the class providing this protected method. See the following example: public class Nano { protected void computeSize() { } } public class NanoContainer extends Nano { protected ArrayList<Nano> children; } public class SomeOtherNode extends NanoContainer { // {Nano} Overrides protected void computeSize() { for (Nano child: children) { child.computeSize(); // << computeSize() has protected access in nanolay.Nano } } } javac tells me that computeSize() has protected access in Nano . I can't see the reason for this

Say I have this Class @interface CustomClass : NSObject @property (nonatomic, strong) NSArray * nicestArrayEver; @end And I want to create a subClass of CustomClass, but here is the catch @interface ASubClassCustomClass : CustomClass @property (nonatomic, strong) NSMutableArray * nicestArrayEver; @end The issue as you can imagine is that when I initialize ASubClassCustomClass and call it's super initializer (since there is other properties required) the inmutable nicestArrayEver is created.. how can I avoid it's creation so I can set the mutable one? Note: This is just an example, the real

I'm making a UIButton subclass in Swift to perform custom drawing and animation on selection What would be the equivalent in Swift of overriding - (void)setSelected:(BOOL)selected in ObjC? I tried override var selected: Bool so I could implement an observer but I get Cannot override with a stored property 'selected' Like others mentioned you can use willSet to detect changes. In an override, however, you do not need assign the value to super, you are just observing the existing change. A couple things you can observe from the following playground: Overriding a property for willSet/didSet still

I am subclassing Numpy's ndarray class, adding some meta-data and additional methods. I'm trying to follow the instructions in this article and that one . However, some Numpy (or Scipy) functions return the base class "ndarray" instead of my custom subclass. Other Numpy functions DO return my subclass, and I don't know what's the reason for the difference. How can I make all the numpy/scipy functions return my subclass? here's what I did: class Signal(np.ndarray): def __new__(cls, filename): #print "In __new__" #TEMP DEBUG ret = np.fromfile(filename, dtype = np.int32) ret = ret.view(cls) #

Does a subclass inherit, the main class' friend associations (both the main class' own and other classes friended with the main class)? Or to put it differently, how does inheritance apply to the friend keyword? To expand: And if not, is there any way to inherit friendship? I have followed Jon's suggestion to post up the design problem: C++ class design questions Friendship is not inherited in C++. The standard says (ISO/IEC 14882:2003, section 11.4.8): Friendship is neither inherited nor transitive. friend only applies to the class you explicitly make it friend and no other class. http://www