充满活力和System.Object的区别 [英] Difference between dynamic and System.Object

问题描述

声明为动态的变量，并声明为System.Object的一个变量之间的区别是什么？运行下面的函数似乎表明，这两个变量会马上转换为正确的类型动态：

 无效ObjectTest（）
{
    System.Object的MyTestVar =测试;
    动态MyTestVar2 =测试123;

    Console.WriteLine（{0}，MyTestVar.GetType（））;
    Console.WriteLine（{0}，MyTestVar2.GetType（））;

    MyTestVar = 123;
    MyTestVar2 = 321;

    Console.WriteLine（{0}，MyTestVar.GetType（））;
    Console.WriteLine（{0}，MyTestVar2.GetType（））;
}
 

解决方案

不同的是， MyTestVar2.ToUpper（）编译和工作，无任何显式类型转换。

对象是一个普通型。
动态是一个基本上是一个占位符类型，导致编译器发出的动态后期绑定调用。

的GetType（）是由对象类，经营上的实例中定义的普通函数的，你就调用它。
的GetType（）是指向你调用它的对象变量的声明的类型完全不受影响。 （除nullables）

What is the difference between a variable declared as dynamic and a variable declared as System.Object? Running the following function would seem to indicate that both variables get cast to the correct type dynamically:

void ObjectTest()
{
    System.Object MyTestVar = "test";
    dynamic MyTestVar2 = "Testing 123";

    Console.WriteLine("{0}", MyTestVar.GetType());
    Console.WriteLine("{0}", MyTestVar2.GetType());

    MyTestVar = 123;
    MyTestVar2 = 321;

    Console.WriteLine("{0}", MyTestVar.GetType());
    Console.WriteLine("{0}", MyTestVar2.GetType());
}

解决方案

The difference is that MyTestVar2.ToUpper() compiles and works, without any explicit casting.

object is a normal type.
dynamic is a basically a placeholder type that causes the compiler to emit dynamic late-bound calls.

GetType() is a normal function defined by the object class that operates on the instance that you call it on.
GetType() is completely unaffected by the declared type of a variable that refers to the object you call it on. (except for nullables)

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