c# - 在实例构造函数之后调用静态构造函数？

Question

亲爱的，像这样的问题已经already asked , 但在答案中没有对我看到的问题的解释。

问题:C# Programming Guide说:

A static constructor is used to initialize any static data, or to perform a particular action that needs performed once only. It is called automatically before the first instance is created or any static members are referenced.

特别是，在创建类的任何实例之前调用静态构造函数。 (这不能确保静态构造函数在创建实例之前完成，但这是另一回事。)

让我们考虑示例代码:

using System;

public class Test
{
    static public Test test = new Test();
    static Test()
    {
        Console.WriteLine("static Test()");
    }
    public Test()
    {
        Console.WriteLine("new Test()");
    }
}

public class Program
{
    public static void Main()
    {
        Console.WriteLine("Main() started");
        Console.WriteLine("Test.test = " + Test.test);
        Console.WriteLine("Main() finished");
    }
}

输出:

Main() started
new Test()
static Test()
Test.test = Test
Main() finished

因此我们可以看到实例构造函数在静态构造函数开始之前完成(因此创建了一个实例)。这不是与指南相矛盾吗？也许静态字段的初始化被认为是静态构造函数的隐式部分？

Answer 1

static 字段的内联初始化器在显式 static 构造函数之前运行。

编译器将您的类转换为如下内容:

public class Test {
    .cctor {    //Class constructor
        Test.test = new Test();                //Inline field initializer
        Console.WriteLine("static Test()");    //Explicit static ctor
    }
    .ctor { ... }    //Instance constructor
}

请注意，这与声明顺序无关。

引用 spec :

The static field variable initializers of a class correspond to a sequence of assignments that are executed in the textual order in which they appear in the class declaration. If a static constructor (Section 10.11) exists in the class, execution of the static field initializers occurs immediately prior to executing that static constructor.