superclass

Java set super instance of instance

由 你说的曾经没有我的故事 提交于 2019-12-07 12:10:50
问题 I might just be unable to google for the right words, but I can't find an answer to the following question. Is it possible to explicitly set the superclass of a new class instance. E.g. I have a SuperClazz instance and want to create a new instance of Clazz which extends SuperClazz . Can I just do something like this (the code is just what I want to do, it doesn't compile and is not correct): class Clazz extends SuperClazz{ Clazz(SuperClazz superInstance){ this.super = superInstance; } } 回答1:

TclOO Variable Scope with Inheritance/superclass

由 ￣綄美尐妖づ 提交于 2019-12-07 08:46:27
I stumbled over the variable scope when inheriting a class with TclOO. The member variable nCrumbs below is not visible to the inherited class without repeating the declaration. Is there a way to avoid replicating all the variable declarations from the superclass? (I read through all the OO documentation, specifically oo::define and oo::object, also the non-exported stuff, googled for it. There are so many concepts to get around various things, I got lost. I am looking for something that keeps the inherited class as simple as possible. The superclass may have any fancy complicated code in it,

How to access a superclass's class attributes in Python?

由 落花浮王杯 提交于 2019-12-07 06:22:38
问题 Have a look at the following code: class A(object): defaults = {'a': 1} def __getattr__(self, name): print('A.__getattr__') return self.get_default(name) @classmethod def get_default(cls, name): # some debug output print('A.get_default({}) - {}'.format(name, cls)) try: print(super(cls, cls).defaults) # as expected except AttributeError: #except for the base object class, of course pass # the actual function body try: return cls.defaults[name] except KeyError: return super(cls, cls).get

ZeroCopyLiteralByteString cannot access superclass

由 和自甴很熟 提交于 2019-12-07 04:00:31
问题描述 在HBase上运行MapReduce作业时，报如下异常：IllegalAccessError: class com.google.protobuf.HBaseZeroCopyByteString cannot access its superclass com.google.protobuf.LiteralByteString 使用HBase环境如下：CDH5.0.1, HBase版本：0.96.1 问题原因 This isssue occurs because of an optimization introduced in HBASE-9867 that inadvertently introduced a classloader dependency. This affects both jobs using the -libjars option and "fat jar," jobs which package their runtime dependencies in a nested lib folder. 这个问题的发生是由于优化了 HBASE-9867 引起的，无意间引进了一个依赖类加载器。它影响使用-libjars参数和使用 fat jar两种模式的job. fat jar模式Hadoop的一个特殊功能：可以读取操作目录中

Javascript Prototype Chaining super class constructor and method calling

由 蹲街弑〆低调 提交于 2019-12-07 03:11:29
问题 I'm a newbie in the JavaScript world, and I came up with this weird problem when i was attempting prototype chaining inheritence. I have 3 classes //class parent function parent(param_1){ this.param = param_1; this.getObjWithParam = function(val){ console.log("value in parent class "+val); console.log("Constructor parameter : "+this.param); }; }; //class child function child(param_1){ this.constructor(param_1); this.getObjWithParam = function(val){ console.log("value in child class "+val);

Do I need to call [super init] or [super initWithCoder], etc for NSObject

由 拥有回忆 提交于 2019-12-06 18:20:05
问题 Typically when I subclass from a UI class I will call the superclass initializer of interest. However, I'm not sure of the implementation details of NSObject , and it seems like there's not much going on in terms of member vars, so I wonder: do I need to call [super init] if my subclass extends NSObject ? 回答1: Technically, no. The documentation for -[NSObject init] says that The init method defined in the NSObject class does no initialization; it simply returns self . Because it is documented

How do you call a method for an Objective-C object's superclass from elsewhere?

由 六眼飞鱼酱① 提交于 2019-12-06 17:28:00
问题 If you're implementing a subclass, you can, within your implementation, explicitly call the superclass's method, even if you've overridden that method, i.e.: [self overriddenMethod]; //calls the subclass's method [super overriddenMethod]; //calls the superclass's method What if you want to call the superclass's method from somewhere outside the subclass's implementation, i.e.: [[object super] overriddenMethod]; //crashes Is this even possible? And by extension, is it possible to go up more

How to cast subclass object to superclass object

由 本秂侑毒 提交于 2019-12-06 13:29:22
i have 2 classes, called superclass and subclass, i tried to cast the subclass object to superclass, but its seems does not work when i want to use the subclass object from the superclass. Please help to explain. Thanks. These are the code:- public class superclass { public void displaySuper() } System.out.println("Display Superclass"); } } public class subclass extends superclass { public void displaySub() { System.out.println("Display Subclass"); } } public class Testing { public static void main(String args[]) { subclass sub = new subclass(); superclass sup = (superclass) sub; when i tried

Calling overridden methods in JavaScript

由 孤街浪徒 提交于 2019-12-06 12:52:08
i tried to find a way to call overridden method of superclass in JS and got this. function A() { this.superclass = new Array(A.prototype); } A.prototype.call_method = function(method, args, pos) { if (!(pos >= 0)) pos = this.superclass.length - 1; while (!this.superclass[pos].hasOwnProperty(method)) if ((--pos) < 0) return; if (this.superclass[pos][method]) this.superclass[pos][method].apply(this, args); if (pos) this.call_method(method, args, pos - 1); } A.prototype.add = function() { this.superclass.push(arguments.callee.caller.prototype); } A.prototype.test = function(a, b, c) { alert("test

Reflection: cast an object to subclass without use instanceof

由 回眸只為那壹抹淺笑 提交于 2019-12-06 04:43:24
问题 I have this simple interface/class: public abstract class Message {} public class Message1 extends Message {} public class Message2 extends Message {} And an utility class: public class Utility { public void handler(Message m) { System.out.println("Interface: Message"); } public void handler(Message1 m) { System.out.println("Class: Message1"); } public void handler(Message2 m) { System.out.println("Class: Message2"); } } Now, the main class: public static void main(String[] args) { Utility p
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