runtime

ios runtime基础知识

由 大兔子大兔子 提交于 2019-12-07 10:00:58
非盈利无广告开发者专用网址导航：www.dev666.com 前言 学习Objective-C的运行时Runtime系统是很有必要的。个人觉得，得之可得天下，失之则失天下。 Objective-C提供了编译运行时，只要有可能，它都可以动态地运作。这意味着不仅需要编译器，还需要运行时系统执行编译的代码。运行时系统充当Objective-C语言的操作系统，有了它才能运作。 运行时系统所提供功能是非常强大的，在实际开发中是经常使用到的。比如，苹果不允许我们给Category追加扩展属性，是因为它不会自动生成成员变量，那么我们通过运行时就可以很好的解决这个问题。另外，常见的模型转字典或者字典转模型，对象归档等。后续我们再来学习如何应用，本节只是讲讲理论。 与Runtime交互 Objective-C程序有有三种与runtime系统交互的级别： 通过Objective-C源代码 通过Foundation库中定义的NSObject提供的方法 通过直接调用runtime方法 通过Objective-C源代码 在大多数的部分，运行时系统会自动运行并在后台运行。我们使用它只是写源代码并编译源代码。当编译包含Objective-C类和方法的代码时，编译器会创建实现了语言动态特性的数据结构和函数调用。该数据结构捕获在类、扩展和协议中所定义的信息。 最重要的runtime函数是发消息函数，在编译时

`repr` and `int` take quadratic time in Python

由 99封情书 提交于 2019-12-07 09:55:30
I was making a table of different run-times for Python 2.7, and noticed a thing that I cannot explain: The run-time of repr(2**n) and int('1'*n) is O(n^2) . I always assumed that converting between integer and string would be O(n) with n being number of digits. The results show that if O(n) fitting gives ~30% error, while O(n^2) is only ~5%. Could anyone explain please. Here are the results that I get (codes are below): Test Number-1 -- time to compute int('1'*n) (fit to O(n**2)) Spec_string: 1000<=n<=10000 by factors of 2 var_list ['n'] Function list: ('n**2', 'n', '1') run times: n = 1000 :

How to scan JAR's, which are loaded at runtime, with Google reflections library?

由 不想你离开。 提交于 2019-12-07 09:41:16
问题 Is there a solution to configure the reflection library so that it scans also JAR's which are added at runtime with URLClassLoader? For now, reflections just scans the URLs in the ClassLoader. This is the configuration which I am using now: Reflections reflections = new Reflections(new ConfigurationBuilder().setUrls(ClasspathHelper.forClassLoader())); I couldn't find any hints in the doc of the reflections library. EDIT: This is how I load the jar File: File f = new File("C:/Users/mkorsch

Is there a way to arbitrarily load Resources at runtime in Android?

由 不打扰是莪最后的温柔 提交于 2019-12-07 08:17:20
问题 I've got some XML resources in my Android app. Each one has a different name like "bicycle.xml" and "car.xml". I'd like to know if there's a way to load resources based on conditions during run time. As an example... Say I had a text input in my app. When the user enters "bicycle", my app can look up an XML resource by that name, parse and load it. Whereas if they enter "car", they would end up with the data from the other XML file. I've noticed so far that to load resources, you have to use

How does function overloading work at run-time, and why overload?

由 生来就可爱ヽ(ⅴ＜●) 提交于 2019-12-07 07:05:19
问题 Let's say I have a class named ClothingStore. That class has 3 member functions, that point a visitor to the right department of the store. Member functions are ChildrenDept, MenDept and WomenDept, depending on whether the visitor is a child, a man or a woman. Function overloading can be used to make 3 functions that have same name, say, PointToDept, but take different input argument ( child, man, woman ). What is actually happening on run-time when program is executing ? My guess is that

Using quotes and double quotes in Java Runtime.getRuntime().exec(…)

由 ⅰ亾dé卋堺 提交于 2019-12-07 06:44:36
问题 I am trying to start a Lisp Image from Java in Mac OSX. Using the Image from my console I type the following: lisp_image --eval '(package::method "some_argument")' everything runs fine. In Java I have the problem to pass the quotes and double quotes using the Runtime.getRuntime().exec("lisp_image --eval '(package::method \"some_argument\")'"). I also tried to use : Runtime.getRuntime().exec(new String[] {"lisp_image", "--eval ", "\'(package::method ", "--eval ", "\"", "some_argument", "\")",

What is the exactly Runtime Host?

由 隐身守侯 提交于 2019-12-07 06:12:28
问题 What is the exactly definition of Runtime Host? From MSDN: The common language runtime has been designed to support a variety of different types of applications, from Web server applications to applications with a traditional rich Windows user interface. Each type of application requires a runtime host to start it. The runtime host loads the runtime into a process, creates the application domains within the process, and loads user code into the application domains. So is it a process which

Java — Runtime typing differences

由 一个人想着一个人 提交于 2019-12-07 05:21:42
问题 I have two situations drawn up, and the strange differences between them are causing me a bit of grief. I will attempt to detail them below in code. Situation 1: public void doSomething(Object obj) { //do something with obj } public void doSomething(String str) { //do something similar to str, but apply some custom //processing for String's } Object o = new String("s"); doSomething(o); // this will use the Object version... Situation 2: class Dog { void makeSound() { System.out.println("woof"

Execution order of Enum in java

由 ℡╲_俬逩灬. 提交于 2019-12-07 04:59:03
问题 I got a question about Enum. I have an enum class looks like below public enum FontStyle { NORMAL("This font has normal style."), BOLD("This font has bold style."), ITALIC("This font has italic style."), UNDERLINE("This font has underline style."); private String description; FontStyle(String description) { this.description = description; } public String getDescription() { return this.description; } } I wonder when this Enum object is created. Enum looks like 'static final' Object since its

How to detect the existence of a class at runtime in .NET?

由 不想你离开。 提交于 2019-12-07 04:53:00
问题 Is it possible in a .NET app (C#), to conditionally detect if a class is defined at runtime? Sample implementation - say you want to create a class object based on a configuration option? 回答1: I've done something like that, load a class from the Config and instantiate it. In this example, I needed to make sure the class specified in the config inherited from a class called NinjectModule, but I think you get the idea. protected override IKernel CreateKernel() { // The name of the class, e.g.
订阅 runtime