If you have multiple classes or traits to inherit, the first one is always extends, and the following >=0 class/trait to be withs. But remember that you can only inherit <=1 (abstract) class, which means if you need to inherit a parent class (Parent), it should always comes at first of the form … extends … Read more
When the Java compiler turns a class into bytecode, it must first look to a parent class. That is because the underlying implementation of classes is to point to the bytecode of the parent class – which holds the relevant methods and fields. Then it adds in pointers to the code of the child class … Read more
Why does it implement its methods? How can it implement its methods when an interface can’t contain method body? How can it implement the methods when it extends the other interface and not implement it? What is the purpose of an interface implementing another interface? Interface does not implement the methods of another interface but … Read more
List<Dog> is a subtype of List<? extends Animal>, but not a subtype of List<Animal>. Why is List<Dog> not a subtype of List<Animal>? Consider the following example: void mySub(List<Animal> myList) { myList.add(new Cat()); } If you were allowed to pass a List<Dog> to this function, you would get a run-time error. EDIT: Now, if we use … Read more
// How to extend Validator interface adding isArray() method?? You cannot do this in a file that is a module (some guidance here) and your file is a module because you have import expressValidator. Instead create a extendedValidator.d.ts and add the new stuff for TypeScript’s engine: declare module ExpressValidator { export interface Validator { isArray: … Read more
class MyModelAdmin(admin.ModelAdmin): … def changelist_view(self, request, extra_context=None): extra_context = extra_context or {} extra_context[‘some_var’] = ‘This is what I want to show’ return super(MyModelAdmin, self).changelist_view(request, extra_context=extra_context) See: https://docs.djangoproject.com/en/dev/ref/contrib/admin/#django.contrib.admin.ModelAdmin.changelist_view
Take a look at Simple JavaScript Inheritance and Inheritance Patterns in JavaScript. The simplest method is probably functional inheritance but there are pros and cons.
What exactly are you trying to achieve? Having two different activities with a common ui, except for some variables or parts of the layout? In this case, I suggest having a base abstract activity, and two concrete inherited subclasses. You define all the common behaviour in the base activity, and have abstract methods for the … Read more
Actually there is an Equivalent(sort of), the where keyword. I don’t know how “close” it is. I had a function I needed to do something similar for. I found an msdn page about it. I don’t know if you can do this inline for a variable, but for a class you can do: public class … Read more
The implements keyword treats the A class as an interface, that means C has to implement all the methods defined in A, no matter if they have an implementation or not in A. Also there are no calls to super methods in C. extends behaves more like what you’d expect from the keyword. You have … Read more