公共字段与自动属性

我们经常被告知，应该通过为类字段创建getter和setter方法(c#中的属性)来保护封装，而不是将字段暴露给外界。

但是很多时候，一个字段只是用来保存一个值，不需要任何计算来获取或设置。对于这些问题，我们都会做这个数字:

public class Book
{
    private string _title;

    public string Title
    {
          get => _title; 
          set => _title = value;
    }
}

好吧，我有一个忏悔，我不能忍受写所有这些(真的，不是必须写它，而是必须看它)，所以我擅自使用了公共字段。

然后出现了c# 3.0，我看到他们添加了自动属性:

public class Book
{
    public string Title { get; set; } 
}

哪个更整洁，我很感激，但说真的，这和仅仅创建一个公共字段有什么不同呢?

public class Book
{
    public string Title;
}

当前回答

我的丈夫做了一些调查

验证。允许重写访问器以更改属性的行为。调试的目的。通过在访问器中设置断点，我们将能够知道属性何时发生变化以及发生了什么变化。我们可以有一个现场布景。例如，public set()和private get()。对于公共字段，这是不可能的。

它确实给了我们更多的可能性和可扩展性。

2020-03-13 19:53:44

其他回答

我的丈夫做了一些调查

它确实给了我们更多的可能性和可扩展性。

2020-03-13 19:53:44

One thing you can do with Fields but not with Properties (or didn't used to be able to ... I'll come to that in a moment) is that Fields can be designated as readonly whereas Properties cannot. So Fields give you a clear way of indicating your intention that a variable is there to be set (from within the constructor) at object-instantiation time only and should not be changed thereafter. Yes, you can set a Property to have a private setter, but that just says "this is not to be changed from outside the class", which is not the same as "this is not to be changed after instantiation" - you can still change it post-instantiation from within the class. And yes you can set the backing field of your property to be readonly, but that moves post-instantiation attempts to change it to being run-time errors rather than compile-time errors. So readonly Fields did something useful which Properties cannot.

然而，这在c# 9中发生了变化，我们得到了下面这些有用的属性语法: