为什么c＃编译器不检查“静态性”的方法在调用站点与动态参数？ [英] Why doesn't the c# compiler check "staticness" of the method at call sites with a dynamic argument?

问题描述

为什么C＃编译器不告诉我这段代码是无效的？

Why doesn't the C# compiler tell me that this piece of code is invalid?

class Program
{
    static void Main(string[] args)
    {
        dynamic d = 1;
        MyMethod(d);
    }

    public void MyMethod(int i) 
    {
        Console.WriteLine("int");
    }
}

调用 MyMethod 在运行时失败，因为我试图从静态方法调用非静态方法。这是非常合理的，但为什么编译器认为这在编译时是错误？

The call to MyMethod fails at runtime because I am trying to call a non-static method from a static method. That is very reasonable, but why doesn't the compiler consider this an error at compile time?

以下将不编译

class Program
{
    static void Main(string[] args)
    {
        dynamic d = 1;
        MyMethod(d);
    }
}

因此尽管动态分派，编译器会检查 MyMethod 存在。为什么不验证静态？

so despite the dynamic dispatch, the compiler does check that MyMethod exists. Why doesn't it verify the "staticness"?

推荐答案

过载分辨率是动态的。在此代码段中可见：

Overload resolution is dynamic here. Visible in this code snippet:

class Program {
    public static void Main() {
        dynamic d = 1.0;
        MyMethod(d);
    }

    public void MyMethod(int i) {
        Console.WriteLine("int");
    }

    public static void MyMethod(double d) {
        Console.WriteLine("double");
    }
}

现在将1分配给d，并记下运行时故障。编译器在编译时不能合理地模拟动态重载解析，所以不会尝试。

Works fine. Now assign 1 to d and note the runtime failure. The compiler cannot reasonably emulate dynamic overload resolution at compile time, so it doesn't try.

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