c# - 这是 C# 4.0 编译器中的错误吗？

Question

这段代码编译成功，但我认为它应该编译失败。此外，当您运行它时，您会得到一个 NullReferenceException。缺少的代码是 Bar 属性初始化中的“new Bar”。

class Bar
{
    public string Name { get; set; }
}

class Foo
{
    public Bar Bar { get; set; }
}


class Program
{
    static void Main(string[] args)
    {
        var foo = new Foo
                      {
                          Bar = { Name = "Hello" }
                      };
    }
}

这是一个已知错误吗？

Answer 1

为什么你认为它应该编译失败？它是嵌套的对象初始化语法，客户端代码负责为初始化提供有效值。

来自文档:

C# 规范 7.5.10.2“对象初始值设定项”

A member initializer that specifies an object initializer after the equals sign is a nested object initializer, i.e. an initialization of an embedded object. Instead of assigning a new value to the field or property, the assignments in the nested object initializer are treated as assignments to members of the field or property