object | 易学教程

CODE - The content of an object is changed after executing a function

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问题 The problem is that the content of $oldpop get magically changed after executing the function func , whereas the input of func is $matepop . Inside func , $oldpop is not used (I added the comment line to show the place - see the end of the code snippet of MAIN.PHP ). Below I provide just some principal parts of the code. Maybe, someone could suggest the reason of the problem? I should mention I don't use static variables. File MAIN.PHP include_once 'func.php'; include_once 'select.php'; class

CODE - The content of an object is changed after executing a function

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C#-关于带参数的单例模式的思考（利用带参数的单例模式连接并查询数据库特定表的信息）

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首先，让我们看一下单例模式是怎样的。 public sealed class Singleton { private static Singleton instance = null; private static readonly object padlock = new object(); Singleton() { } public static Singleton Instance { get { if (instance == null) { lock (padlock) { if (instance == null) { instance = new Singleton(); } } } return instance; } } } 这是<<C# in Depth>>这本书中提供的标准代码。实现单例模式的思路是：定义一个密封类(sealed)以避免其它类继承此类（据书中所说此举虽然不是必要的，但可以帮助JIT进行更多优化）。定义并初始化该类自身的静态实例(instance)为null,用该instance来检测控制在创建单例模式的类的程序中只有一个该类的实例。定义并初始化一个只读(readonly)的用于锁(lock)的object对象以满足多线程环境。创建一个只有get方法的该类的静态变量，用于创建该类的实例。最后在该类的构造函数中写入相关代码。

Unsafe类

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一、Unsafe类仅能被BootstrapClassLoader加载的类实例化，用户建的类默认都是ApplicationClassLoader加载的，实例化Unsafe时会报错。可以用反射实例化（方式一）。补充：加启动参数指定当前类由BootstrapClassLoader加载（方式二） private Unsafe() {//构造方法私有化同单例模式防止new } @CallerSensitive public static Unsafe getUnsafe() { Class var0 = Reflection.getCallerClass(); if (!VM.isSystemDomainLoader(var0.getClassLoader())) {//判断是否BootstrapClassLoader加载的类执行实例化的 throw new SecurityException("Unsafe"); } else { return theUnsafe; } } 二、反射实现实例化 public class UnsafeTest2 { static final Unsafe unsafe; static final long stateOffset; private volatile long state = 0; static { try { Field field =

Adding objects to an array

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问题 I have been looking at questions of how to add elements to an array How can I dynamically add items to a Java array?. I do not understand how to add objects of a class type, not a datatype like String . How am I supposed to do this, when the object patient has various datatypes? What I can't get my head around, is how to put the attributes of a Patient object into an array. Class Patient{ public Patient(String ptNo, String ptName, int procType) throws IOException { Patient.patientNo = ptNo;

Building class names form strings

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问题 I have an array of strings like this: tableArray: { "Map", "Web", "Help" + 10 other strings} The array is used to build the table cells in a UITableViewController. When tapped I want the appropriate view controller to show, in the didSelectRowAtIndexPath method. Instead of creating a large switch, or if .. then .. else statement, can I somehow create the class name from the strings above, so that Map becomes MapViewController: MapViewController *detailViewController = [[MapViewController

Animating two images in java

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问题 I'm quite new to java. I need to animate two images on a java game. It's meant to be a spaceship game allowing two users to control the objects, using a keyboard. I've partially implemented this, however I cannot understand how to allow for two keyboard controls, and also the one object that is moving via keyboard input is flickering a lot. public class MainFrame extends JFrame implements KeyListener { MainPanel mPanel; MainPanel secondss; MainPanel thirdss; int speed = 5; //ss facing north

Where/how to delete an object within another object, outside the function that it was created in

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问题 In order to solve this problem Bad memory management? Class member (boolean) value greater than 1, in recursion function, I ran the whole program under Valgrind and found a few memory leak problems that occurred before the step. There were 2 'definitely lost' problems identified in the function CMFLoader. (here MyDataset is a vector of Molecule objects, and each Molecule object contains an Elements object) In CMFLoader::loadFile(vector& MyDataset), I originally have MyDataset.push_back(

Proper way to load a base class + extended class in PHP

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问题 I am working on a personal project and it is the first time for me using OOP. My project has a base class, which is extended by others (basic setup). To clarify, this is what I am doing: Base class: class ABC { function __construct() { ... } } Extending class: class DEF extends ABC { function __construct() { ... } } While the base class is always loaded, the other classes are loaded depending of the situation. My question is, what is the proper way to dynamically load the right extended class

Javascript “this” variable confusion

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问题 I am currently reading the book "Javascript: The Good Parts" and was playing with Functions. I produced a test script to test some properties and I am somewhat confused by the results. Here is the code: <h3>Object</h3> <div style="padding-left: 10px;"> <script type="text/javascript"> function outterF() { document.writeln("outterF.this = " + this + "<br>"); function innerF() { document.writeln("innerF.this = " + this + "<br>"); return this; }; var inner = innerF(); return this; } document