c# - 使用成员函数启动线程

Question

我最近遇到了这样一段代码(这里是简化版，我检查过它并且有效):

using System;
using System.Threading;

namespace Rextester
{
    public class Program
    {
        public class Foo
        {
            public Foo()
            {
                thread = new Thread(new ThreadStart(Loop));
            }

            private void Loop()
            {
            }

            private Thread thread;
        }
        public static void Main(string[] args)
        {
            var foo = new Foo();
            Console.WriteLine("How does it work??");
        }
    }
}

为什么这样的代码可以正常工作而没有编译器的任何提示？据我了解，线程应该从应该是静态的函数开始。 (或者无论如何都应该传递对对象和成员函数的引用)。但在这里我只看到传递对成员函数的引用。好像我错过了 C# 中的大事。可能存在传递 this 引用的隐式方式吗？

UPD:非常感谢。我只想补充一点这个事实。事实证明，编译器会自动处理委托(delegate)(传递正确的引用对象和方法)。这是 il 代码:

.method public hidebysig specialname rtspecialname 
        instance void  .ctor() cil managed
{
  // Code size       32 (0x20)
  .maxstack  8
  IL_0000:  ldarg.0
  IL_0001:  call       instance void [mscorlib]System.Object::.ctor()
  IL_0006:  nop
  IL_0007:  nop
  IL_0008:  ldarg.0
  IL_0009:  ldarg.0
  IL_000a:  ldftn      instance void Rextester.Program/Foo::Loop()
  IL_0010:  newobj     instance void 
[mscorlib]System.Threading.ThreadStart::.ctor(object,

native int)
  IL_0015:  newobj     instance void 
[mscorlib]System.Threading.Thread::.ctor(class 
[mscorlib]System.Threading.ThreadStart)
  IL_001a:  stfld      class [mscorlib]System.Threading.Thread 
Rextester.Program/Foo::thread
  IL_001f:  ret
} // end of method Foo::.ctor

Answer 1

But here I see only passing reference to member function.

文档对 ThreadStart 说它是一个委托(delegate)。它

"represents the method that executes on a Thread.
When a managed thread is created, the method that executes on the thread is represented by a ThreadStart delegate"

---

Thread should start from function which should be static.

这不一定是真的。该函数不必是静态的。

文档显示了这两个示例。使用静态方法和使用实例方法:

class Test
{
    static void Main() 
    {
        // To start a thread using a static thread procedure, use the
        // class name and method name when you create the ThreadStart
        // delegate. Beginning in version 2.0 of the .NET Framework,
        // it is not necessary to create a delegate explicitly. 
        // Specify the name of the method in the Thread constructor, 
        // and the compiler selects the correct delegate. For example:
        //
        // Thread newThread = new Thread(Work.DoWork);
        //
        ThreadStart threadDelegate = new ThreadStart(Work.DoWork);
        Thread newThread = new Thread(threadDelegate);
        newThread.Start();

        // To start a thread using an instance method for the thread 
        // procedure, use the instance variable and method name when 
        // you create the ThreadStart delegate. Beginning in version
        // 2.0 of the .NET Framework, the explicit delegate is not
        // required.
        //
        Work w = new Work();
        w.Data = 42;
        threadDelegate = new ThreadStart(w.DoMoreWork);
        newThread = new Thread(threadDelegate);
        newThread.Start();
    }
}

class Work 
{
    public static void DoWork() 
    {
        Console.WriteLine("Static thread procedure."); 
    }
    public int Data;
    public void DoMoreWork() 
    {
        Console.WriteLine("Instance thread procedure. Data={0}", Data); 
    }
}

编辑:

关于类型委托(delegate) documentation说:

A delegate is a type that represents references to methods with a particular parameter list and return type.

在此tutorial on MSDN on deleagates您可以看到如何使用 new 关键字实例化它:

Instantiating a delegate Once a delegate type has been declared, a delegate object must be created and associated with a particular method. Like all other objects, a new delegate object is created with a new expression.

这意味着由于 Loop 和 ThreadStart 具有相同的返回类型，即 void 和相同的参数列表，(此处为空)你可以使用实例方法 Loop 的名称实例化委托(delegate)。

编辑 2:

I just was confused about using member function without reference.

这是可行的，因为您在与声明方法的位置相同的类中声明了线程。

May be there is implicit way of passing this reference?

在这种情况下，答案是肯定的。如果您在类中调用方法或使用名称作为委托(delegate)(指向方法的指针)，则 this 是隐式的。