static

Const static variable defined in header file has same address in different translation unit

由 好久不见. 提交于 2020-01-02 18:06:08
问题 I have checked out the definition of std::ios::app in /usr/include/c++/4.6/bits/ios_base.h and found that std::ios::app is defined as a const static variable: typedef _Ios_Openmode openmode; /// Seek to end before each write. static const openmode app = _S_app; in which _Ios_Openmode is defined in the same header file as enum _Ios_Openmode { _S_app = 1L << 0, _S_ate = 1L << 1, _S_bin = 1L << 2, _S_in = 1L << 3, _S_out = 1L << 4, _S_trunc = 1L << 5, _S_ios_openmode_end = 1L << 16 }; It's well

Learning OO coding with PHP, static != expressions, but PHP manual says everything that has a value is an expression, confused

由 人走茶凉 提交于 2020-01-02 08:24:13
问题 I started to learn OO a few days back, I'm quite OK with procedural coding but obviously that is not enough and I want to become a well versed coder with a lot of experience and knowledge, so first thing to learn completely must be OO followed by the right design patterns I think. Anyhow, I have one thing where I'm stuck which I don't quite follow... Static variables... I understand that a static variable doesn't lose it's value even if the containing function is finished executing, and will

Will a static variable always use up memory?

由 北城以北 提交于 2020-01-02 07:42:13
问题 Based on this discussion, I was wondering if a function scope static variable always uses memory or if the compiler is allowed to optimize that away. To illustrate the question, assume a function like such: void f() { static const int i = 3; int j = i + 1; printf("%d", j); } The compiler will very likely inline the value of i and probably do the calculation 3 + 1 at compile time, too. Since this is the only place the value of i is used, there is no need for any static memory being allocated.

Public static methods - a bad sign?

由 不羁的心 提交于 2020-01-02 07:20:14
问题 I've just read this article here: http://hamletdarcy.blogspot.com/2008/04/10-best-idea-inspections-youre-not.html, and the last bit in particular got me thinking about my code, specifically the advice: What in the world is a public method doing on your object that has no dependency on any fields within the object? This is certainly a code smell. The problem is that the "auto-fix" for the inspection is to apply the static keyword. Nooooo. That's not what you want to do. A public method without

How to pass data between activities using static variables on a public class?

由 久未见 提交于 2020-01-02 07:18:49
问题 I'm trying to use static variables on a public class for passing them between activities. I'm having a rare problem doing that. I'm giving values to the static variables on a activity. This activity calls a GLSurfaceView and listen for screen orientation changes. If i give values to the static variables on the GLSurfaceView, then, all works fine, the values are stored and i can retrieve them when the onCreate method is called again after a screen orientation change. The problem is when i

WCF Static Variable Getting Reset with Each Call

由 ╄→гoц情女王★ 提交于 2020-01-02 06:40:29
问题 I have a WCF service that I am calling from multiple clients. I need to store and manage a value globally. On my service I have the following attributes: [ServiceBehavior(InstanceContextMode = InstanceContextMode.Single, ConcurrencyMode = ConcurrencyMode.Single)] In my service I have something similar to this: private static int counter; public void PrintCounter() { counter++; StreamWriter sw = new StreamWriter(@"C:\outFile.txt", true); sw.WriteLine("Counter: " + counter); sw.Close(); } With

Why doesn't my static block of code execute?

由 半世苍凉 提交于 2020-01-02 06:31:22
问题 I am trying to run this code, I but found out this behavior of final with static: the code runs without executing static block of A. Please provide me with the reason. class A { final static int a=9; static { //this block is not executing ?? System.out.println("static block of A"); } } class Manager { static { System.out.println("manager sib"); } public static void main(String ...arg) { System.out.println("main"); System.out.println(A.a); } } Why doesn't the static block of Class A run? 回答1:

ASP.NET Core开发之HttpContext

由 一世执手 提交于 2020-01-02 02:38:24
ASP.NET Core中的HttpContext开发，在ASP.NET开发中我们总是会经常用到HttpContext。 那么在ASP.NET Core中要如何使用HttpContext呢，下面就来具体学习ASP.NET Core HttpContext。 注入HttpContextAccessor ASP.NET Core中提供了一个 IHttpContextAccessor接口，HttpContextAccessor 默认实现了它简化了访问HttpContext。 它必须在程序启动时在IServicesCollection中注册，这样在程序中就能获取到HttpContextAccessor，并用来访问HttpContext。 services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>(); 获取HttpContextAccessor 下面来实际做一个操作，获取 HttpContextAccessor。 新建一个ASP.NET Core Web 应用程序，选择Web 应用程序。 身份验证勾选为不进行身份验证。 然后在HomeController 加入如下代码: public class HomeController : Controller { private IHttpContextAccessor

Java: Why no warning when referencing a field before it is defined?

由 孤街醉人 提交于 2020-01-02 01:09:36
问题 A static field cannot be referenced before it is defined or initialized: static Integer j = i; /* compile error */ static final Integer i = 5; However, when it is referenced from an instance initialization block (in an anonymous inner class), not even a warning is generated. See example: class StaticInitialization { static final Object o = new Object() {{ j = i; }}; static Integer j, k; static final Integer i = 5; static final Object o2 = new Object() {{ k = i; }}; } The result is: j == null

Javascript es6 override static properties

由 笑着哭i 提交于 2020-01-01 11:50:33
问题 Trying out ES6 and tried to create a class with static properties and function for parsing. Then I want to extend the base parser for each different type I am parsing. Not sure if I am doing a anti-pattern but I cannot override static properties. This is my base parser class Module { static name = 'Default Module' static version = {major:10000, minor: 10000} static checkVersion({majorVersion = 10000, minorVersion = 10000}) { if(this.version.major !== majorVersion || this.version.minor >
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