如何使用 Visual Studio（和/或 ReSharper）从类字段生成构造函数？

Posted 2023-03-28

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【中文标题】如何使用 Visual Studio（和/或 ReSharper）从类字段生成构造函数？【英文标题】：How do I generate a constructor from class fields using Visual Studio (and/or ReSharper)? 【发布时间】：2011-02-27 21:57:39 【问题描述】：

我已经习惯了许多 Java IDE（Eclipse、NetBeans 和 IntelliJ IDEA）为您提供了一个命令来根据类中的字段为类生成默认构造函数。

例如：

public class Example

    public decimal MyNumber  get; set; 
    public string Description  get; set; 
    public int SomeInteger  get; set; 

    // ↓↓↓ This is what I want generated ↓↓↓
    public Example(decimal myNumber, string description, int someInteger)
    
        MyNumber = myNumber;
        Description = description;
        SomeInteger = someInteger;

在大多数 OOP 语言中，让构造函数填充对象的所有字段是一项非常常见的任务，我假设有某种方法可以节省用 C# 编写此样板代码的时间。我是 C# 世界的新手，所以我想知道我是否遗漏了该语言的一些基本知识？ Visual Studio 中是否有一些显而易见的选项？

【问题讨论】：

【参考方案1】：

ReSharper 提供了一个Generate Constructor 工具，您可以在其中选择要初始化的任何字段/属性。我使用 Alt + Ins 热键来访问它。

【讨论】：

这回答了我关于“完成它”的问题。但是，VS2010中并没有直接支持，对吧？就像 Jared 在下面提到的那样，VS2010 添加了一个“从使用情况生成”工具，但据我所知，没有办法根据类中已经存在的字段生成构造函数。如果您尝试使用与任何现有签名都不匹配的签名来实例化该类，它将提供为您生成该构造函数。哦，哇，我知道这是一个相当老的问题，但我才发现这个！您可能应该提到 ReSharper 不是免费的。【参考方案2】：

C# 在 Visual Studio 2010 中添加了一项新功能，称为从使用中生成。目的是从使用模式生成标准代码。其中一项功能是根据初始化模式生成构造函数。

可通过检测到模式时出现的智能标签访问该功能。

例如，假设我有以下课程

class MyType

我在我的应用程序中写了以下内容

var v1 = new MyType(42);

采用int 的构造函数不存在，因此将显示一个智能标记，其中一个选项将是“生成构造函数存根”。选择它会将MyType 的代码修改为以下内容。

class MyType 
    private int p;
    public MyType(int p) 
        // TODO: Complete member initialization
        this.p = p;

【讨论】：

【参考方案3】：

您可以编写一个宏来执行此操作 - 您可以使用 Visual Studio 的解析器来检索有关该类成员的信息。

我写了一个类似的宏。（我将在下面分享代码）。我编写的宏用于在继承基类时将所有构造函数向前复制（对于像 Exception 这样在 ctor 上有很多重载的类很有用）。

这是我的宏（同样，它不能解决您的问题，但您可以修改以做您想做的事）


Imports System
Imports EnvDTE
Imports EnvDTE80
Imports EnvDTE90
Imports EnvDTE100
Imports System.Diagnostics

Public Module ConstructorEditor
    Public Sub StubConstructors()
        'adds stubs for all of the constructors in the current class's base class
        Dim selection As TextSelection = DTE.ActiveDocument.Selection
        Dim classInfo As CodeClass2 = GetClassElement()

        If classInfo Is Nothing Then
            System.Windows.Forms.MessageBox.Show("No class was found surrounding the cursor.  Make sure that this file compiles and try again.", "Error")
            Return
        End If

        If classInfo.Bases.Count = 0 Then
            System.Windows.Forms.MessageBox.Show("No parent class was found for this class.  Make sure that this file, and any file containing parent classes compiles and try again")
            Return
        End If

        'setting up an undo context -- one ctrl+z undoes everything
        Dim closeUndoContext As Boolean = False
        If DTE.UndoContext.IsOpen = False Then
            closeUndoContext = True
            DTE.UndoContext.Open("StubConstructorsContext", False)
        End If

        Try
            Dim parentInfo As CodeClass2 = classInfo.Bases.Item(1)
            Dim childConstructors As System.Collections.Generic.List(Of CodeFunction2) = GetConstructors(classInfo)
            Dim parentConstructors As System.Collections.Generic.List(Of CodeFunction2) = GetConstructors(parentInfo)
            For Each constructor As CodeFunction2 In parentConstructors
                If Not MatchingSignatureExists(constructor, childConstructors) Then
                    ' we only want to create ctor stubs for ctors that are missing
                    ' note: a dictionary could be more efficient, but I doubt most classes will have more than 4 or 5 ctors...
                    StubConstructor(classInfo, constructor)
                End If
            Next
        Finally
            If closeUndoContext Then
                DTE.UndoContext.Close()
            End If
        End Try
    End Sub
    Private Function GetConstructors(ByVal classInfo As CodeClass2) As System.Collections.Generic.List(Of CodeFunction2)
        ' return a list of all of the constructors in the specified class
        Dim result As System.Collections.Generic.List(Of CodeFunction2) = New System.Collections.Generic.List(Of CodeFunction2)
        Dim func As CodeFunction2
        For Each member As CodeElement2 In classInfo.Members
            ' members collection has all class members.  filter out just the function members, and then of the functions, grab just the ctors
            func = TryCast(member, CodeFunction2)
            If func Is Nothing Then Continue For
            If func.FunctionKind = vsCMFunction.vsCMFunctionConstructor Then
                result.Add(func)
            End If
        Next
        Return result
    End Function
    Private Function MatchingSignatureExists(ByVal searchFunction As CodeFunction2, ByVal functions As System.Collections.Generic.List(Of CodeFunction2)) As Boolean
        ' given a function (searchFunction), searches a list of functions where the function signatures (not necessarily the names) match
        ' return null if no match is found, otherwise returns first match
        For Each func As CodeFunction In functions
            If func.Parameters.Count <> searchFunction.Parameters.Count Then Continue For
            Dim searchParam As CodeParameter2
            Dim funcParam As CodeParameter2
            Dim match As Boolean = True

            For count As Integer = 1 To searchFunction.Parameters.Count
                searchParam = searchFunction.Parameters.Item(count)
                funcParam = func.Parameters.Item(count)
                If searchParam.Type.AsFullName <> funcParam.Type.AsFullName Then
                    match = False
                    Exit For
                End If
            Next

            If match Then
                Return True
            End If
        Next
        ' no match found
        Return False
    End Function

    Private Sub StubConstructor(ByVal classInfo As CodeClass2, ByVal parentConstructor As CodeFunction2)
        ' adds a constructor to the current class, based upon the parentConstructor that is passed in

        ' highly inefficient hack to position the ctor where I want it (after the last ctor in the class, if there is another ctor
        ' note that passing zero as the position (put the ctor first) caused some problems when we were adding ctors to classes that already had ctors
        Dim position As Object
        Dim ctors As System.Collections.Generic.List(Of CodeFunction2) = GetConstructors(classInfo)

        If ctors.Count = 0 Then
            position = 0
        Else
            position = ctors.Item(ctors.Count - 1)
        End If

        ' if there are no other ctors, put this one at the top
        Dim ctor As CodeFunction2 = classInfo.AddFunction(classInfo.Name, vsCMFunction.vsCMFunctionConstructor, vsCMTypeRef.vsCMTypeRefVoid, position, parentConstructor.Access)

        Dim baseCall As String = ":base("
        Dim separator As String = ""
        For Each parameter As CodeParameter2 In parentConstructor.Parameters
            ctor.AddParameter(parameter.Name, parameter.Type, -1)
            baseCall += separator + parameter.Name
            separator = ", "
        Next
        baseCall += ")"

        ' and 1 sad hack -- appears to be no way to programmatically add the :base() calls without using direct string manipulation
        Dim startPoint As TextPoint = ctor.GetStartPoint()
        Dim endOfSignature As EditPoint = startPoint.CreateEditPoint()
        endOfSignature.EndOfLine()
        endOfSignature.Insert(baseCall)
        startPoint.CreateEditPoint().SmartFormat(endOfSignature)
    End Sub

    Private Function GetClassElement() As CodeClass2
        'returns a CodeClass2 element representing the class that the cursor is within, or null if there is no class
        Try
            Dim selection As TextSelection = DTE.ActiveDocument.Selection
            Dim fileCodeModel As FileCodeModel2 = DTE.ActiveDocument.ProjectItem.FileCodeModel
            Dim element As CodeElement2 = fileCodeModel.CodeElementFromPoint(selection.TopPoint, vsCMElement.vsCMElementClass)
            Return element
        Catch
            Return Nothing
        End Try
    End Function

End Module

【讨论】：

缺少一个运算符：" If searchParam.Type.AsFullName funcParam.Type.AsFullName Then" 应该是 " If searchParam.Type.AsFullName = funcParam.Type.AsFullName Then" @LTR 很好——除了它应该是“如果 searchParam.Type.AsFullName funcParam.Type.AsFullName ”。我错过了尖括号上的转义——它们出现在编辑器中，但不在视图中。谢谢！【参考方案4】：

这是我用于此目的的宏。它将从具有私有 setter 的字段和属性生成构造函数。

Imports System
Imports EnvDTE
Imports EnvDTE80
Imports EnvDTE90
Imports EnvDTE90a
Imports EnvDTE100
Imports System.Diagnostics
Imports System.Collections.Generic

Public Module Temp

    Sub AddConstructorFromFields()
        DTE.UndoContext.Open("Add constructor from fields")

        Dim classElement As CodeClass, index As Integer
        GetClassAndInsertionIndex(classElement, index)

        Dim constructor As CodeFunction
        constructor = classElement.AddFunction(classElement.Name, vsCMFunction.vsCMFunctionConstructor, vsCMTypeRef.vsCMTypeRefVoid, index, vsCMAccess.vsCMAccessPublic)

        Dim visitedNames As New Dictionary(Of String, String)
        Dim element As CodeElement, parameterPosition As Integer, isFirst As Boolean = True
        For Each element In classElement.Children
            Dim fieldType As String
            Dim fieldName As String
            Dim parameterName As String

            Select Case element.Kind
                Case vsCMElement.vsCMElementVariable
                    Dim field As CodeVariable = CType(element, CodeVariable)
                    fieldType = field.Type.AsString
                    fieldName = field.Name
                    parameterName = field.Name.TrimStart("_".ToCharArray())

                Case vsCMElement.vsCMElementProperty
                    Dim field As CodeProperty = CType(element, CodeProperty)
                    If field.Setter.Access = vsCMAccess.vsCMAccessPrivate Then
                        fieldType = field.Type.AsString
                        fieldName = field.Name
                        parameterName = field.Name.Substring(0, 1).ToLower() + field.Name.Substring(1)
                    End If
            End Select

            If Not String.IsNullOrEmpty(parameterName) And Not visitedNames.ContainsKey(parameterName) Then
                visitedNames.Add(parameterName, parameterName)

                constructor.AddParameter(parameterName, fieldType, parameterPosition)

                Dim endPoint As EditPoint
                endPoint = constructor.EndPoint.CreateEditPoint()
                endPoint.LineUp()
                endPoint.EndOfLine()

                If Not isFirst Then
                    endPoint.Insert(Environment.NewLine)
                Else
                    isFirst = False
                End If

                endPoint.Insert(String.Format(MemberAssignmentFormat(constructor.Language), fieldName, parameterName))

                parameterPosition = parameterPosition + 1
            End If
        Next

        DTE.UndoContext.Close()

        Try
            ' This command fails sometimes '
            DTE.ExecuteCommand("Edit.FormatDocument")
        Catch ex As Exception
        End Try
    End Sub
    Private Sub GetClassAndInsertionIndex(ByRef classElement As CodeClass, ByRef index As Integer, Optional ByVal useStartIndex As Boolean = False)
        Dim selection As TextSelection
        selection = CType(DTE.ActiveDocument.Selection, TextSelection)

        classElement = CType(selection.ActivePoint.CodeElement(vsCMElement.vsCMElementClass), CodeClass)

        Dim childElement As CodeElement
        index = 0
        For Each childElement In classElement.Children
            Dim childOffset As Integer
            childOffset = childElement.GetStartPoint(vsCMPart.vsCMPartWholeWithAttributes).AbsoluteCharOffset
            If selection.ActivePoint.AbsoluteCharOffset < childOffset Or useStartIndex Then
                Exit For
            End If
            index = index + 1
        Next
    End Sub
    Private ReadOnly Property MemberAssignmentFormat(ByVal language As String) As String
        Get
            Select Case language
                Case CodeModelLanguageConstants.vsCMLanguageCSharp
                    Return "this.0 = 1;"

                Case CodeModelLanguageConstants.vsCMLanguageVB
                    Return "Me.0 = 1"

                Case Else
                    Return ""
            End Select
        End Get
    End Property
End Module

【讨论】：

我不得不将这一行：“If Not String.IsNullOrEmpty(parameterName) And NotvisitedNames.ContainsKey(parameterName) Then”分成两行以避免空引用异常：【参考方案5】：

也许你可以试试这个：http://cometaddin.codeplex.com/

【讨论】：

CodePlex 已关闭（但该链接目前仍然有效，带有可下载的存档）。但也许尝试更新链接（如果项目已移至其他地方）。和/或如果当前的链接将来损坏，请采取措施防止灾难发生。【参考方案6】：

我正在使用以下技巧：

我选择带有数据成员的类的声明，然后按：

Ctrl+C, Shift+Ctrl+C, Ctrl+V.

第一个命令将声明复制到剪贴板，第二个命令是调用程序的快捷方式最后一个命令用剪贴板中的文本覆盖所选内容。

程序从剪贴板获取声明，查找类的名称，查找所有成员及其类型，生成构造函数并将其全部复制回剪贴板。

我们正在与我的“Programming-I”实践中的新生一起做这件事（查尔斯大学，布拉格）并且大多数学生会在一个小时结束之前完成。

如果您想查看源代码，请告诉我。

【讨论】：

第二个命令是类视图的快捷方式，不是吗？或者这个提示不是关于 Visual Studio 2010 的？【参考方案7】：

这里是 JMarsh 的 Visual Studio 宏修改为根据类中的字段和属性生成构造函数。

Imports System
Imports EnvDTE
Imports EnvDTE80
Imports EnvDTE90
Imports EnvDTE100
Imports System.Diagnostics
Imports System.Collections.Generic

Public Module ConstructorEditor

    Public Sub AddConstructorFromFields()

        Dim classInfo As CodeClass2 = GetClassElement()
        If classInfo Is Nothing Then
            System.Windows.Forms.MessageBox.Show("No class was found surrounding the cursor.  Make sure that this file compiles and try again.", "Error")
            Return
        End If

        ' Setting up undo context. One Ctrl+Z undoes everything
        Dim closeUndoContext As Boolean = False
        If DTE.UndoContext.IsOpen = False Then
            closeUndoContext = True
            DTE.UndoContext.Open("AddConstructorFromFields", False)
        End If

        Try
            Dim dataMembers As List(Of DataMember) = GetDataMembers(classInfo)
            AddConstructor(classInfo, dataMembers)
        Finally
            If closeUndoContext Then
                DTE.UndoContext.Close()
            End If
        End Try

    End Sub

    Private Function GetClassElement() As CodeClass2
        ' Returns a CodeClass2 element representing the class that the cursor is within, or null if there is no class
        Try
            Dim selection As TextSelection = DTE.ActiveDocument.Selection
            Dim fileCodeModel As FileCodeModel2 = DTE.ActiveDocument.ProjectItem.FileCodeModel
            Dim element As CodeElement2 = fileCodeModel.CodeElementFromPoint(selection.TopPoint, vsCMElement.vsCMElementClass)
            Return element
        Catch
            Return Nothing
        End Try
    End Function

    Private Function GetDataMembers(ByVal classInfo As CodeClass2) As System.Collections.Generic.List(Of DataMember)

        Dim dataMembers As List(Of DataMember) = New List(Of DataMember)
        Dim prop As CodeProperty2
        Dim v As CodeVariable2

        For Each member As CodeElement2 In classInfo.Members

            prop = TryCast(member, CodeProperty2)
            If Not prop Is Nothing Then
                dataMembers.Add(DataMember.FromProperty(prop.Name, prop.Type))
            End If

            v = TryCast(member, CodeVariable2)
            If Not v Is Nothing Then
                If v.Name.StartsWith("_") And Not v.IsConstant Then
                    dataMembers.Add(DataMember.FromPrivateVariable(v.Name, v.Type))
                End If
            End If

        Next

        Return dataMembers

    End Function

    Private Sub AddConstructor(ByVal classInfo As CodeClass2, ByVal dataMembers As List(Of DataMember))

        ' Put constructor after the data members
        Dim position As Object = dataMembers.Count

        ' Add new constructor
        Dim ctor As CodeFunction2 = classInfo.AddFunction(classInfo.Name, vsCMFunction.vsCMFunctionConstructor, vsCMTypeRef.vsCMTypeRefVoid, position, vsCMAccess.vsCMAccessPublic)

        For Each dataMember As DataMember In dataMembers
            ctor.AddParameter(dataMember.NameLocal, dataMember.Type, -1)
        Next

        ' Assignments
        Dim startPoint As TextPoint = ctor.GetStartPoint(vsCMPart.vsCMPartBody)
        Dim point As EditPoint = startPoint.CreateEditPoint()
        For Each dataMember As DataMember In dataMembers
            point.Insert("            " + dataMember.Name + " = " + dataMember.NameLocal + ";" + Environment.NewLine)
        Next

    End Sub

    Class DataMember

        Public Name As String
        Public NameLocal As String
        Public Type As Object

        Private Sub New(ByVal name As String, ByVal nameLocal As String, ByVal type As Object)
            Me.Name = name
            Me.NameLocal = nameLocal
            Me.Type = type
        End Sub

        Shared Function FromProperty(ByVal name As String, ByVal type As Object)

            Dim nameLocal As String
            If Len(name) > 1 Then
                nameLocal = name.Substring(0, 1).ToLower + name.Substring(1)
            Else
                nameLocal = name.ToLower()
            End If

            Return New DataMember(name, nameLocal, type)

        End Function

        Shared Function FromPrivateVariable(ByVal name As String, ByVal type As Object)

            If Not name.StartsWith("_") Then
                Throw New ArgumentException("Expected private variable name to start with underscore.")
            End If

            Dim nameLocal As String = name.Substring(1)

            Return New DataMember(name, nameLocal, type)

        End Function

    End Class

End Module

【讨论】：

【参考方案8】：

您可以使用 ReSharper 8 或更高版本轻松完成此操作。 ctorf、ctorp 和 ctorfp sn-ps 生成构造函数，用于填充类的所有字段、属性或字段和属性。

【讨论】：

【参考方案9】：

对于 Visual Studio 2015，我发现 an extension 就是这样做的。它似乎运行良好，并且下载量相当高。因此，如果您不能或不想使用 ReSharper，您可以安装它。

您也可以通过via NuGet获取。

【讨论】：

【参考方案10】：

在 Visual Studio 2015 Update3 中，我有这个功能。

只需突出显示属性，然后按Ctrl + 。，然后按生成构造函数。

例如，如果您突出显示了两个属性，它会建议您创建一个带有两个参数的构造函数，如果您选择了三个，它会建议一个带有三个参数的构造函数，依此类推。

它也适用于 Visual Studio 2017 和 2019。

【讨论】：

嘿，这在 Visual Studio 2015 社区中对我有用。不知道这不是很为人所知，但这很好。谢谢。 :) 那是完美的。如果我在你发布它的那天读到它，这本可以保存的工作...... xD 不管怎样，如果您使用 C# 6 只读属性，该功能不会弹出。（例如，public int Age get; ）他们需要指定 at 设置器，即使是临时的，以使选项可用。在 VS2015 社区测试；不确定这是否已在 VS2017 中修复。 @PouyaSamie：在 C# 6.0 中，可以在构造函数中分配只读自动属性。请参阅此示例：github.com/dotnet/roslyn/wiki/… 这是完美的解决方案！我会将此标记为真正的解决方案！【参考方案11】：

从 Visual Studio 2017 开始，这似乎是一项内置功能。当您的光标位于类主体中时按 Ctrl + .，然后从 Quick Actions and Refactorings"Generate Constructor" /em> 下拉菜单。

【讨论】：