vb6相当于list <someclass>

Question

vb6相当于list <someclass>

我想知道是否存在等价的(.net)

list<somefixedclass>

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在vb6中

我知道vb6中存在集合,但它使用对象(变体)而不是特定对象.

谢谢.

Answer 1

Cod*_*ray 22

VB 6中没有List<T>与VB.NET中的通用等效的直接等价物.然而,Collection在VB 6中存在这样的事物,其提供类似的功能.的主要区别在于,VB 6 Collection是不强类型,这意味着所有的对象被存储为Variants藏.在某些情况下,这可能是有益的,因为它允许您在同一个集合中存储许多不同类型的数据,事实上,VB在内部使用此对象.Collection从类中检索它们时,使用和上传对象很容易,但是你可以做的很少.在VB运行时中无法实现强类型集合.

话虽如此,您可以实施一种解决方法.类似于在引入泛型之前如何在早期版本的VB.NET中实现集合,您可以将其包装Collection在一个类中,其中对内部的唯一访问Collection是通过从此类公开的方法.此设计模式通常称为"自定义集合".

这确实具有自动处理转换的好处,并且减轻了代码的使用者必须记住这样的实现细节.它会处理(很可能)您在运行时循环遍历集合的可能性,该集合只应包含一种类型的对象,但意外地添加了第二种不兼容的对象类型,导致您的代码抛出异常.当然,缺点是您必须以Collection自定义集合上的公共方法的形式重新实现对象本身提供的大部分功能.

以下是您可能会如何做到这一点的示例:

Public Class CustomerCollection

    ''#Internal collection, exposed by this class
    Private m_Customers As Collection

    Private Sub Class_Initialize()
        ''#Set up the internal collection
        Set m_Customers = New Collection
    End Sub

    Public Sub Add(ByVal cust as Customer, Optional ByVal key as String)
        ''#Add the Customer object to the internal collection
        If IsMissing(key) Then
            m_Customers.Add cust
        Else
            m_Customers.Add cust, key
        End If
    End Sub

    Public Property Get Count() As Integer
        ''#Return the number of objects in the internal collection
        Count = m_Customers.Count
    End Property

    Public Sub Remove(ByVal index As Variant)
        ''#Remove the specified object from the internal collection,
        ''# either by its index or its key
        m_Customers.Remove index
    End Sub

    Public Function Item(ByVal index As Variant) as Customer
        ''#Return the specified object from the internal collection,
        ''# either by its index or its key
        Set Item = m_Customers.Item(index)
    End Function

    Public Sub Clear()
        ''#Removes all objects from the internal collection
        Set m_Customers = New Collection
    End Sub

End Class

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请注意,为了将自定义集合的Item属性设置为集合的默认方法(如内置Collection对象),您需要在VB 6 IDE中执行以下步骤:

从"工具"菜单中,单击"过程属性"
从"名称"组合框中选择自定义类的名称.
出现对话框时,单击"高级"按钮.
在"过程ID"组合框中选择"(默认)"项.
点击"确定"

如果您还想使用For Each语法(也像内置Collection对象)允许枚举自定义类,则可以NewEnum向自定义类添加一个函数:

Public Property Get NewEnum() As IUnknown
    ''#Provides support for enumeration using For Each
    Set NewEnum = m_Customers.[_NewEnum]
End Property

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完成后,您需要指示VB使用此属性:

和以前一样,从"工具"菜单中打开"过程属性"对话框
从"名称"组合框中选择自定义类的名称.
出现对话框时,单击"高级"按钮.
在"过程ID"组合框中键入数字"-4".
点击"确定"

+1但是不要自己创建样板.Francesco Balena写了[CollectionClassMaster](http://www.angryhacker.com/download/colclassmaster.zip),这是一个免费的VB6 IDE插件,可以自动为你完成.现在由[AngryHacker](http://angryhacker.com/blog/archive/2008/05/01/vb6-swiss-army-knife.aspx)主持. (2认同)

Answer 2

Kri*_*son 5

这是我们的ArrayList实现.对于强类型类,您可以将它用作基础(不是通过显然继承,而是通过CodyGray的答案中表达的组合),但如果您不需要类型安全,则它比Collection类好得多.

Option Explicit

Private mavInternalArray() As Variant
Private mlArraySize As Long
Private mlCount As Long
Private mlGrowSize As Long
Private mfZeroIndex As Boolean

'---------------------------------------------------------------------------------------
' Procedure Clear
'---------------------------------------------------------------------------------------
Public Sub Clear()
          Dim index As Long

        For index = 0 To mlCount - 1
            If IsObject(mavInternalArray(index)) Then
                Set mavInternalArray(index) = Nothing
            End If
        Next index
        mlCount = 0

End Sub



'---------------------------------------------------------------------------------------
' Procedure Swap
'---------------------------------------------------------------------------------------
Public Sub Swap(Index1 As Long, index2 As Long)
          Dim vTmp As Variant


        If IsObject(mavInternalArray(index2)) Then
            Set vTmp = mavInternalArray(index2)
        Else
            vTmp = mavInternalArray(index2)
        End If

        If IsObject(mavInternalArray(Index1)) Then
            Set mavInternalArray(index2) = mavInternalArray(Index1)
        Else
           mavInternalArray(index2) = mavInternalArray(Index1)
       End If

       If IsObject(vTmp) Then
           Set mavInternalArray(Index1) = vTmp
       Else
           mavInternalArray(Index1) = vTmp
       End If


End Sub

Public Property Get ZeroIndex() As Boolean
        ZeroIndex = mfZeroIndex
End Property

Public Property Let ZeroIndex(fZeroIndex As Boolean)
        mfZeroIndex = fZeroIndex
End Property

Public Property Get GrowSize() As Long
        GrowSize = mlGrowSize
End Property

Public Property Let GrowSize(lNewSize As Long)
        Debug.Assert lNewSize > 0
        mlGrowSize = lNewSize
End Property

Private Sub Class_Initialize()
        mlGrowSize = 50
        mlArraySize = mlGrowSize
        mfZeroIndex = True
        mlCount = 0


        ReDim mavInternalArray(0 To mlGrowSize - 1)

End Sub

'---------------------------------------------------------------------------------------
' Procedure Remove
'---------------------------------------------------------------------------------------
Public Sub Remove(index As Long)
        Dim index2 As Long


        For index2 = index To mlCount - 2
            If IsObject(mavInternalArray(index2 + 1)) Then
                Set mavInternalArray(index2) = mavInternalArray(index2 + 1)
            Else
                mavInternalArray(index2) = mavInternalArray(index2 + 1)
            End If
        Next index2
          If mlCount <= 0 Then
            Exit Sub
          End If
        mlCount = mlCount - 1
        If IsObject(mavInternalArray(mlCount)) Then
           Set mavInternalArray(mlCount) = Nothing
       Else
           mavInternalArray(mlCount) = False
       End If
End Sub

'---------------------------------------------------------------------------------------
' Procedure Items
'---------------------------------------------------------------------------------------
Public Function Items(index As Long) As Variant
        If Not mfZeroIndex Then
            index = index - 1
        End If

        If index < mlCount And index >= 0 Then
            If IsObject(mavInternalArray(index)) Then
                Set Items = mavInternalArray(index)
            Else
                Items = mavInternalArray(index)
            End If
       End If
End Function

Public Sub SetItem(index As Long, Item As Variant)
        If Not mfZeroIndex Then
            index = index - 1
        End If
        If IsObject(Item) Then
            Set mavInternalArray(index) = Item
        Else
            mavInternalArray(index) = Item
        End If
End Sub

'---------------------------------------------------------------------------------------
' Procedure Add
'---------------------------------------------------------------------------------------
Public Function Add(vItem As Variant) As Long

        mlCount = mlCount + 1
        If mlCount > mlArraySize Then
            mlArraySize = mlArraySize + mlGrowSize
            ReDim Preserve mavInternalArray(0 To mlArraySize - 1)
        End If

        If IsObject(vItem) Then
            Set mavInternalArray(mlCount - 1) = vItem
        Else
            mavInternalArray(mlCount - 1) = vItem
       End If

       Add = mlCount - 1

End Function

'---------------------------------------------------------------------------------------
' Procedure ItemArray
'---------------------------------------------------------------------------------------
Public Function ItemArray() As Variant
        Dim vReturnArray As Variant

        vReturnArray = mavInternalArray
        ReDim Preserve vReturnArray(0 To mlCount - 1)
        ItemArray = vReturnArray
End Function

Public Function Count() As Long
        Count = mlCount
End Function


'---------------------------------------------------------------------------------------
' Procedure Insert
'---------------------------------------------------------------------------------------
Public Function Insert(index As Long, vItem As Variant) As Long
        Dim index2 As Long

        'Make sure array is large enough for a new item
        mlCount = mlCount + 1
        If mlCount > mlArraySize Then
            mlArraySize = mlArraySize + mlGrowSize
            ReDim Preserve mavInternalArray(0 To mlArraySize - 1)
        End If

        'Bump all the items with a higher index up one spot

        If index >= mlCount - 1 Then
            If IsObject(vItem) Then
                Set mavInternalArray(mlCount - 1) = vItem
            Else
               mavInternalArray(mlCount - 1) = vItem
           End If
       Else

           For index2 = mlCount - 1 To index + 1 Step -1
               If IsObject(vItem) Then
                   Set mavInternalArray(index2) = mavInternalArray(index2 - 1)
               Else
                   mavInternalArray(index2) = mavInternalArray(index2 - 1)
               End If
           Next index2

           If IsObject(vItem) Then
               Set mavInternalArray(index) = vItem
           Else
               mavInternalArray(index) = vItem
           End If
       End If
       Insert = mlCount - 1

End Function


Public Sub Clone(ByRef cDestinationDynamicArray As clsDynamicArray)
        Dim index As Long

        If cDestinationDynamicArray Is Nothing Then
            Set cDestinationDynamicArray = New clsDynamicArray
        End If

        cDestinationDynamicArray.Clear

        For index = 0 To mlCount - 1
            Call cDestinationDynamicArray.Add(mavInternalArray(index))
        Next index

End Sub

Public Property Get NewEnum() As IUnknown
    ''#Provides support for enumeration using For Each
    Set NewEnum = m_Customers.[_NewEnum]
End Property

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