Обобщения и ограничения типов

Class Box(Of T)
    Public Property Value As T
    Public Sub New(value As T)
        Me.Value = value
    End Sub
End Class
Module Demo
    Sub Main()
        Dim item = New Box(Of Integer)(3)
        Console.WriteLine(item.Value + 1)
    End Sub
End Module

Option Strict On
Namespace ReviewCase11_1
    Class Box(Of T)
        Public Property Value As T
        Public Sub New(value As T)
            Me.Value = value
        End Sub
    End Class
    Module Demo
        Sub Main()
            Dim reviewItem = New Box(Of Integer)(7)
            Console.WriteLine(reviewItem.Value + 1)
        End Sub
    End Module
End Namespace

Option Explicit On
Option Infer On
Namespace BoundaryCase11_1
    Class Box(Of T)
        Public Property Value As T
        Public Sub New(value As T)
            Me.Value = value
        End Sub
    End Class
    Module Demo
        Sub Main()
            Dim edgeItem = New Box(Of Integer)(1)
            Console.WriteLine(edgeItem.Value + 1)
        End Sub
    End Module
End Namespace

Class Factory(Of T As {Class, New})
    Public Function Create() As T
        Return New T()
    End Function
End Class

Option Strict On
Namespace ReviewCase11_2
    Class Factory(Of T As {Class, New})
        Public Function Create() As T
            Return New T()
        End Function
    End Class
End Namespace

Option Explicit On
Option Infer On
Namespace BoundaryCase11_2
    Class Factory(Of T As {Class, New})
        Public Function Create() As T
            Return New T()
        End Function
    End Class
End Namespace

Module Demo
    Function FirstOrDefaultValue(Of T)(items As IEnumerable(Of T)) As T
        For Each item In items
            Return item
        Next
        Return Nothing
    End Function

    Sub Main()
        Dim empty = Array.Empty(Of Integer)()
        Console.WriteLine(FirstOrDefaultValue(empty))
    End Sub
End Module

Option Strict On
Namespace ReviewCase11_3
    Module Demo
        Function FirstOrDefaultValue(Of T)(reviewItems As IEnumerable(Of T)) As T
            For Each reviewItem In reviewItems
                Return reviewItem
            Next
            Return Nothing
        End Function

        Sub Main()
            Dim reviewEmpty = Array.Empty(Of Integer)()
            Console.WriteLine(FirstOrDefaultValue(reviewEmpty))
        End Sub
    End Module
End Namespace

Option Explicit On
Option Infer On
Namespace BoundaryCase11_3
    Module Demo
        Function FirstOrDefaultValue(Of T)(edgeItems As IEnumerable(Of T)) As T
            For Each edgeItem In edgeItems
                Return edgeItem
            Next
            Return Nothing
        End Function

        Sub Main()
            Dim edgeEmpty = Array.Empty(Of Integer)()
            Console.WriteLine(FirstOrDefaultValue(edgeEmpty))
        End Sub
    End Module
End Namespace

Interface IProducer(Of Out T)
    Function GetValue() As T
End Interface
Interface IConsumer(Of In T)
    Sub Accept(value As T)
End Interface

Option Strict On
Namespace ReviewCase11_4
    Interface IProducer(Of Out T)
        Function GetValue() As T
    End Interface
    Interface IConsumer(Of In T)
        Sub Accept(value As T)
    End Interface
End Namespace

Option Explicit On
Option Infer On
Namespace BoundaryCase11_4
    Interface IProducer(Of Out T)
        Function GetValue() As T
    End Interface
    Interface IConsumer(Of In T)
        Sub Accept(value As T)
    End Interface
End Namespace

Module Demo
    Function MaxValue(Of T As IComparable(Of T))(items As IEnumerable(Of T)) As T
        Using it = items.GetEnumerator()
            If Not it.MoveNext() Then Throw New InvalidOperationException("empty")
            Dim best = it.Current
            While it.MoveNext()
                If it.Current.CompareTo(best) > 0 Then best = it.Current
            End While
            Return best
        End Using
    End Function
End Module

Option Strict On
Namespace ReviewCase11_5
    Module Demo
        Function MaxValue(Of T As IComparable(Of T))(reviewItems As IEnumerable(Of T)) As T
            Using it = reviewItems.GetEnumerator()
                If Not it.MoveNext() Then Throw New InvalidOperationException("empty")
                Dim reviewBest = it.Current
                While it.MoveNext()
                    If it.Current.CompareTo(reviewBest) > 0 Then reviewBest = it.Current
                End While
                Return reviewBest
            End Using
        End Function
    End Module
End Namespace

Option Explicit On
Option Infer On
Namespace BoundaryCase11_5
    Module Demo
        Function MaxValue(Of T As IComparable(Of T))(edgeItems As IEnumerable(Of T)) As T
            Using it = edgeItems.GetEnumerator()
                If Not it.MoveNext() Then Throw New InvalidOperationException("empty")
                Dim edgeBest = it.Current
                While it.MoveNext()
                    If it.Current.CompareTo(edgeBest) > 0 Then edgeBest = it.Current
                End While
                Return edgeBest
            End Using
        End Function
    End Module
End Namespace