“ =”是什么意思？声明属性时在.Net C＃中做什么？ [英] What does "=>" do in .Net C# when declaring a property?

问题描述

我已经在.NET 4.6.1 C＃项目中看到了这种属性声明

I've seen this kind of property declaration in a .NET 4.6.1 C# project

public object MyObject => new object();

我习惯于声明只读属性，例如：

I'm used to declaring read only properties like this:

public object MyObject { get; }

我知道两者之间存在一些差异（第一个会创建一个新对象），但是我想要更深入的说明以及何时使用它们的一些指示。

I understand that there are some differences between the two (the first one creates a new object), but I would like a deeper explanation as well as some indications of when to use either of them.

推荐答案

第一个使用新的-to-C＃-6 表达式主体成员语法。等效于：

The first uses the new-to-C#-6 expression-bodied member syntax. It's equivalent to:

public object MyObject
{
    get { return new object(); }
}

第二个也是C＃6的也是 -自动实现的只读属性。等效于：

The second is also new to C# 6 - an automatically implemented read-only property. It's equivalent to:

private readonly object _myObject; // Except using an unspeakable name
public object MyObject
{
    get { return _myObject; }
}

您只能分配给 MyObject 来自声明类中的构造函数，实际上只是分配给该字段。

You can only assign to MyObject from within a constructor in the declaring class, which actually just assigns to the field instead.

（这两个等价物都使用了老式的属性声明，您总是将 get ， set 设置为一个或两个都包含代码的块。）

(Both of these "equivalencies" are using old-school property declarations, where you always have get, set or both as blocks containing code.)

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