吸气属性没有人叫它运行 [英] Getter property is run without anyone calling it

问题描述

我在.NET 3.5的工作。
我有一个A级具有堆栈和一个getter属性，它被调用时，将删除在栈中的第一项，并检索下一个。

初始化类后，我看到的getter作品，未经被调用，并在栈中删除顶部的项目，从而使我坏的结果。在吸气的断点并没有表现出任何人穿过它。

在我的属性更改为一个函数，堆栈返回ok了。

$ B $ ; b

我会很高兴，如果有人能解释这是为什么。

下面是简化类：

 大众A级
 {
私人堆叠式和LT;字符串>网址; 
 
公开发行A（字符串名称，String []数组），
 {
的url =新的堆栈<串GT;（）; 
的foreach（字符串s数组）
 {
 Urls.Push（S）; 
} 
} 
 
公共字符串地址
 {
 {返回Urls.Peek（）; } 
} 
公共字符串NextUrl 
 {
获得{
如果（Urls.Count→1）
 {Urls.Pop（）; } 
返回Urls.Peek（）; 
}; 
} 
} 
  

解决方案

首先，使得属性访问器更改状态通常是一个坏主意。它应该做的最多的就是懒洋洋地初始化的东西 - 或者可能给挥发性值（如 DateTime.Now 一样）

其次，你可能会看到这一点，如果你在调试器下运行 - 当你执行代码，它访问性能。这可能会解释为什么断点没有被击中了。

I'm working in .net 3.5. I have a class "A" which has a stack and a getter property which, when called, removes the first item in the stack and retrieves the next one.

After initializing the class, I saw that the getter works without being called, and removes the top item in the stack, thus giving me bad results. A breakpoint in the getter did not show anyone passing through it.

When I change the property to a function, the stack is returned ok.

I'd be happy if someone could explain why is that.

Here is the simplified class:

 public class A
    {
        private Stack<string> Urls;

        public A(string title, string[] array)
        {
            Urls = new Stack<string>();
            foreach (string s in array)
            {
                Urls.Push(s);
            }
        }

        public string Url
        {
            get { return Urls.Peek(); }
        }
        public string NextUrl
        {
            get{
            if (Urls.Count > 1)
                { Urls.Pop(); } 
            return Urls.Peek(); 
            };
        }            
    }

解决方案

Firstly, making a property accessor change the state is generally a bad idea. The most it should do is lazily initialize something - or possibly give a volatile value (like DateTime.Now does).

Secondly, you're probably seeing this if you're running under the debugger - it accesses properties while you're stepping through code. That would probably explain why the breakpoint wasn't being hit, too.

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