为什么要对原始值使用表达式主体属性?

问题描述

表达式实体属性与直接属性声明的优缺点是什么?例如，使用;

What are the pros and cons of expression-bodied properties vs straight property declarations? For example, is there any advantage to using;

public string Foo => "Bar"

对比简单

public string Foo = "Bar"

我的理解是 => 用于值来自方法(如 lambda 函数)时.如果值是像字符串或整数这样的原始值，为什么有人会为此使用表达式主体属性?

My understanding was the => is used when the value comes from a method, like a lambda function. If the value is a primitive like a string or int, why would anyone use an expression-bodied property for that?

推荐答案

这两行代码有不少区别:

There are quite a few differences between those two lines of code:

1. 第一个是属性，第二个是字段.例如，你不能ref第一个Foo.
2. 属性每次都会被评估并返回一个新对象，即使该对象是相同的字符串文字.变量被评估一次，使用时它只是加载.(请注意，编写 #1 的更好方法是 public string Foo { get; } = "Bar";，它也将被初始化一次，然后返回相同的值.
3. 第一个是只读的(它只是一个 getter)，而第二个是一个可变变量，你可以写入它.更接近的等价物是 public readonly string Foo = "Bar"; 或者更好的 public static readonly string Foo = "Bar";

1. The first one is a property, the second is a field. For example, you cannot ref the first Foo.
2. The property gets evaluated and returns a new object every time, even if the object is the same string literal. The variable is evaluated once and when used it's just loaded. (Note that a better way to write #1 is public string Foo { get; } = "Bar"; which would also be initialized once and then return the same value).
3. The first one is read-only (it's a getter only), while the second one is a mutable variable, you can write into it. A closer equivalent would be public readonly string Foo = "Bar"; or even better public static readonly string Foo = "Bar";

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