subclass

问题 Say I have a Class called ParentClass and a Class called ChildClass The ParentClass is abstract and the ChildClass extends the ParentClass per Java terminology. Furthermore, the ParentClass has a constructor which takes an int as a parameter. Now in another class I want to instantiate the ChildClass . I have tried the two below ways: ChildClass obj1 = new ChildClass(5) ParentClass obj2 = new ChildClass(5) Java allows me to use any of the two above ways. My question is, is there actually any

问题 Is it possible to redefine which object the brackets [] use? I can subclass the list object, but how to I make the interpreter use my subclass in place of the buildin list object? Is it possible? (I'm pretty sure I'm using the wrong terms for the question- feel free to edit) >>> class mlist(list): ... def __init__(self): ... list.__init__(self) ... def __getitem__(self, item): ... return list.__getitem__(self, item) * 2 ... >>> testlist = mlist() >>> testlist.append(21) >>> testlist[0] 42 >>>

问题 The below Code works but not as i wish.i want that when i click UIbutton its automaically update the new value in UITableview instead of old value.Below Code works only when i press the UIbuttons and after that when i scroll the UITableview then it update the UItableview with new values. In my application i using UITableview as Subclass of my mainclass.as image show below I add Tableview in my Mainclass which is "testingViewController" like this way In testingViewController.h #import

问题 I'm using subclasses in my django-models like this: class Person(models.Model): name = models.CharField(max_length=100) ... class Butcher(Person): ... class Driver(Person): ... In my view i want to do certain things depending on the subclass of the Person-class, like this: def person_detail_view(request, slug): person = Person.objects.get(slug=slug) if person.butcher: ... elif person.driver: ... But this gives me a DoesNotExist-Error when the Person is a Driver. Is there a way to ask the

问题 Im overriding an equals() method and I need to know if the object is an instance of a Event's subclass (Event is the superclass). I want something like "obj subclassof Event". How can this be made? Thanks in advance! 回答1: instanceof can handle that just fine. 回答2: With the following code you can check if an object is a class that extends Event but isn't an Event class instance itself. if(myObject instanceof Event && myObject.getClass() != Event.class) { // then I'm an instance of a subclass

问题 Im overriding an equals() method and I need to know if the object is an instance of a Event's subclass (Event is the superclass). I want something like "obj subclassof Event". How can this be made? Thanks in advance! 回答1: instanceof can handle that just fine. 回答2: With the following code you can check if an object is a class that extends Event but isn't an Event class instance itself. if(myObject instanceof Event && myObject.getClass() != Event.class) { // then I'm an instance of a subclass

问题 I need a container that can collect a number of objects and provides some reporting functionality on the container's elements. Essentially, I'd like to be able to do: magiclistobject = MagicList() magiclistobject.report() ### generates all my needed info about the list content So I thought of subclassing the normal list and adding a report() method. That way, I get to use all the built-in list functionality. class SubClassedList(list): def __init__(self): list.__init__(self) def report(self):

问题 I'm trying to create & use a very simple UIView subclass for a rectangle with rounded corners. I've created a new class as follows : RoundedRect.h #import <UIKit/UIKit.h> #import <QuartzCore/QuartzCore.h> @interface RoundedRect : UIView @end RoundedRect.m #import "RoundedRect.h" @implementation RoundedRect - (id)initWithFrame:(CGRect)frame { self = [super initWithFrame:frame]; if (self) { // Initialization code [[self layer] setCornerRadius:10.0f]; [[self layer] setMasksToBounds:YES]; }

问题 I'd like to create a subclass programatically. I guess I have few options - Javassist, CGLib, BCEL, or ASM. The use case is that one app's internals are class-oriented, and extensions are class-based. Therefore I can't have a single class as a base for multiple extensions driven by externalized scripts. Now - how would I do that? I've found examples with intercepting method calls, field access, initialization etc. But nothing about subclassing. I'd like to end up with a class which: has a

问题 Customizing pprint.PrettyPrinter The documentation for the pprint module mentions that the method PrettyPrinter.format is intended to make it possible to customize formatting. I gather that it's possible to override this method in a subclass, but this doesn't seem to provide a way to have the base class methods apply line wrapping and indentation. Am I missing something here? Is there a better way to do this (e.g. another module)? Alternatives? I've checked out the pretty module, which looks