什么是自动实现的字段 [英] What is an auto-implemented field

问题描述

我有一个带有以下 Property 的 vb Class:

I have a vb Class with the following Property in it:

公共财产总线为整数

这是否等同于更详细的属性?

Is this equivalent to a more detailed property?

编译器是否真的在后台将这行代码转换为更详细的Property 结构，其中包含一个字段_Buses?

Does the compiler actually transform, in the background, this line of code into a more detailed Property structure which includes a field _Buses?

因此，只要我使用结构 Public Property x AS y，无需实际声明 _Buses，那么这些字段之一将可用吗?

Therefore without actually declaring _Buses aslong as I use the structure Public Property x AS y then one of these fields will be available?

编辑
实际上不太确定是否可以添加比 此处在 MSDN 上

推荐答案

Short Answers

问:编译器是否真的在后台将这行代码转换为包含字段_Buses的更详细的属性结构?
答:是

Short Answers

Q: Does the compiler actually transform, in the background, this line of code into a more detailed Property structure which includes a field _Buses?
A: Yes

问:无需实际声明 _Buses 只要我使用结构 Public Property x AS y 那么这些字段之一将可用吗?
答:是

Q: Without actually declaring _Buses aslong as I use the structure Public Property x AS y then one of these fields will be available?
A: Yes

---

自动实现的属性通常是您没有为属性的 Get 和 Set 部分明确指定代码的属性.自动实现属性的一般定义如下:

Auto-implemented properties are generally properties where you do not explicitly specify code for the Get and Set parts of the property. The general definition of an auto-implemented property is as follows:

Public Property Age As Integer

或

Public Property Age As Integer = 5

在这两种情况下，编译器都会自动为您生成所有支持字段和初始值设定项.

In both cases, the compiler generates all the backing fields and initializers for you automatically.

考虑以下具有两个自动实现的属性(Name 和 Age)和一个常规属性(Address)的类.

Consider the following class with two auto-implemented properties (Name and Age) and one regular property (Address).

Public Class Person

    Dim _address As String

    Public Sub New()
        _address = "4, Hutchinson Road"
    End Sub    

    Public Property Name As String
    Public Property Age As Integer = 3
    Public Property Address As String
        Get
            Return _address
        End Get
        Set(value As String)
            _address = value
        End Set
    End Property

    Public Overrides Function ToString() As String
        Return _Name & " Age: " & Me.Age.ToString()
    End Function
End Class

编译器自动为 Name 和 Age 属性生成支持字段以及 Get 和 Set 方法.生成的字段与前面带有下划线的属性同名.因此，Name 属性的支持字段是 _Name，而 Age 属性的支持字段是 _Age.

The compiler automatically generates backing fields as well as Get and Set methods for the Name and Age properties. The fields generated have the same name as the property with a preceding underscore. Therefore the Name property's backing field is _Name and the Age property's backing field is _Age.

自动生成的字段还附加了 DebuggerBrowsable(DebuggerBrowsableState.Never) 和 CompilerGenerated 属性.

The auto-generated fields also have the DebuggerBrowsable(DebuggerBrowsableState.Never) and CompilerGenerated attributes attached to them.

DebuggerBrowsable 属性可防止该字段显示在代码编辑器的自动完成列表中.但是，这并不妨碍您直接在代码中访问该字段，正如您在 ToString 方法中看到的那样，我直接使用了 _Name 字段.
CompilerGenerated 属性表明该字段是由编译器创建的.

The DebuggerBrowsable attributes prevents the field from being displayed in the Auto-Complete list in the code editor. This, however, does not prevent you from accessing the field directly in your code, as you can see in the ToString method where I use the _Name field directly.
The CompilerGenerated attribute indicates that the field was created by the compiler.

Age 属性(以及所有带有初始化器的自动实现的属性)在类的默认构造函数中初始化.

The Age property (as well as all auto-implemented properties with initializers) is initialized in the class's default constructor.

上述类的反编译版本如下所示:

The decompiled version of the class above looks like this:

Public Class Person
    ' Methods
    Public Sub New()
        Me.Age = 3
        Me._address = "4, Hutchinson Road"
    End Sub

    Public Overrides Function ToString() As String
        Return String.Join(" ", New String() { Me._Name, Me.Age.ToString })
    End Function


    ' Properties
    Public Property Address As String
        Get
            Return Me._address
        End Get
        Set(ByVal value As String)
            Me._address = value
        End Set
    End Property

    Public Property Age As Integer
        <DebuggerNonUserCode> _
        Get
            Return Me._Age
        End Get
        <DebuggerNonUserCode> _
        Set(ByVal AutoPropertyValue As Integer)
            Me._Age = AutoPropertyValue
        End Set
    End Property

    Public Property Name As String
        <DebuggerNonUserCode> _
        Get
            Return Me._Name
        End Get
        <DebuggerNonUserCode> _
        Set(ByVal AutoPropertyValue As String)
            Me._Name = AutoPropertyValue
        End Set
    End Property


    ' Fields
    Private _address As String
    <CompilerGenerated, DebuggerBrowsable(DebuggerBrowsableState.Never)> _
    Private _Age As Integer
    <DebuggerBrowsable(DebuggerBrowsableState.Never), CompilerGenerated> _
    Private _Name As String
End Class

如您所见，字段 _Name 和 _Age 是自动生成的，因此您可以在代码中使用它们而不会出现任何问题.

As you can see, the fields _Name and _Age are generated for you automatically so you can use them in your code without any problems.

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