superclass

问题 This question is in relation to posts at What does 'super' do in Python? , How do I initialize the base (super) class? , and Python: How do I make a subclass from a superclass? which describes two ways to initialize a SuperClass from within a SubClass as class SuperClass: def __init__(self): return def superMethod(self): return ## One version of Initiation class SubClass(SuperClass): def __init__(self): SuperClass.__init__(self) def subMethod(self): return or class SuperClass: def __init__

问题 This question is in relation to posts at What does 'super' do in Python? , How do I initialize the base (super) class? , and Python: How do I make a subclass from a superclass? which describes two ways to initialize a SuperClass from within a SubClass as class SuperClass: def __init__(self): return def superMethod(self): return ## One version of Initiation class SubClass(SuperClass): def __init__(self): SuperClass.__init__(self) def subMethod(self): return or class SuperClass: def __init__

问题 I know that super() and multi-inheritance have already been discussed here. But I did not find a solution, regarding my specific problem in python3. Let's assume we have: #! /usr/bin/env python3 class A(object): def __init__(self): super().__init__() def foo(self): print("The") class B(object): def __init__(self): super().__init__() def foo(self): print("world") class C(B): def __init__(self): super().__init__() def foo(self): super().foo() print("is") class D(A,C): def __init__(self): super(

问题 According to the docs, super(cls, obj) returns a proxy object that delegates method calls to a parent or sibling class of type cls I understand why super() offers this functionality, but I need something slightly different: I need to create a proxy object that delegates methods calls (and attribute lookups) to class cls itself; and as in super , if cls doesn't implement the method/attribute, my proxy should continue looking in the MRO order (of the new not the original class). Is there any

问题 All the ExtJS documentation and examples I have read suggest calling superclass methods like this: MyApp.MyPanel = Ext.extend(Ext.Panel, { initComponent: function() { // do something MyPanel specific here... MyApp.MyPanel.superclass.initComponent.call(this); } }); I have been using this pattern for quite some time and the main problem is, that when you rename your class then you also have to change all the calls to superclass methods. That's quite inconvenient, often I will forget and then I

问题 I was reading 'Dive Into Python' and in the chapter on classes it gives this example: class FileInfo(UserDict): "store file metadata" def __init__(self, filename=None): UserDict.__init__(self) self["name"] = filename The author then says that if you want to override the __init__ method, you must explicitly call the parent __init__ with the correct parameters. What if that FileInfo class had more than one ancestor class? Do I have to explicitly call all of the ancestor classes' __init__

问题 This question already has answers here : Why do this() and super() have to be the first statement in a constructor? (19 answers) Closed 3 years ago . I have the following 2 classes public class classA { classA() { System.out.println("A"); } } class classB extends classA { classB() { System.out.println("B"); } } and then running 1 classA c = new classB(); or 2 classB c = new classB(); always gives A B Why is this happening? At first glance, in either scenario, I would assume that only the

问题 How to inherit the constructor from a super class to a sub class? 回答1: Constructors are not inherited, you must create a new, identically prototyped constructor in the subclass that maps to its matching constructor in the superclass. Here is an example of how this works: class Foo { Foo(String str) { } } class Bar extends Foo { Bar(String str) { // Here I am explicitly calling the superclass // constructor - since constructors are not inherited // you must chain them like this. super(str); }

问题 How to inherit the constructor from a super class to a sub class? 回答1: Constructors are not inherited, you must create a new, identically prototyped constructor in the subclass that maps to its matching constructor in the superclass. Here is an example of how this works: class Foo { Foo(String str) { } } class Bar extends Foo { Bar(String str) { // Here I am explicitly calling the superclass // constructor - since constructors are not inherited // you must chain them like this. super(str); }

问题 I am trying to do some polymorphism exercises and I cannot figure out how this kind of polymorphism works. I did not find any deep information about this kind of exercised. I hope you guys could give me some explanation. exercise 1: class Top { public void m( Middle p ) System.out.print("A "); } class Middle extends Top { public void m( Object p ) System.out.print("M "); public void m( Middle p ) System.out.print("L "); } class Bottom extends Middle { public void m( Object p ) System.out