Question

How do I create my own primitive? For example an integer that has a range of to 1-10.

EDIT: This came from a task on Rosetta Code.

Defining Primitive Data Types: Demonstrate how to define a type that behaves like an integer but has a lowest valid value of 1 and a highest valid value of 10.

I added it here because I thought it might be useful to others.

Answer 1

Structure LimitedInt   Implements IComparable(Of LimitedInt)   Implements IEquatable(Of LimitedInt)    Private m_Value As Integer 'treat the default, 0 as being really 1'    Public ReadOnly Property Value() As Integer    Get      Return If(m_Value = 0, 1, m_Value)    End Get   End Property    Public Sub New(ByVal value As Integer)    If value < 1 Or value > 10 Then        Throw New ArgumentOutOfRangeException('value')    End If    m_Value = value   End Sub    Public Function CompareTo(ByVal other As LimitedInt) As Integer _       Implements System.IComparable(Of LimitedInt).CompareTo    Return Me.Value - other.Value   End Function    Public Overloads Function Equals(ByVal other As LimitedInt) As Boolean _      Implements System.IEquatable(Of LimitedInt).Equals    Return Me.Value = other.Value   End Function    Public Overrides Function GetHashCode() As Integer    Return Value.GetHashCode   End Function    Public Overrides Function Equals(ByVal obj As Object) As Boolean    If TypeOf obj Is LimitedInt Then Return CType(obj, LimitedInt) = Me   End Function    Public Shared Operator =(ByVal left As LimitedInt, _      ByVal right As LimitedInt) As Boolean    Return left.Equals(right)   End Operator    Public Shared Operator <>(ByVal left As LimitedInt, _      ByVal right As LimitedInt) As Boolean    Return Not (left = right)   End Operator    Public Shared Operator +(ByVal left As LimitedInt, _      ByVal right As LimitedInt) As LimitedInt    Dim temp As Integer = left.Value + right.Value    Select Case temp      Case 1 To 10 : Return New LimitedInt(temp)      Case Else : Throw New OverflowException    End Select   End Operator    Public Shared Operator -(ByVal left As LimitedInt, _      ByVal right As LimitedInt) As LimitedInt    Dim temp As Integer = left.Value - right.Value    Select Case temp      Case 1 To 10 : Return New LimitedInt(temp)      Case Else : Throw New OverflowException    End Select   End Operator    Public Shared Operator *(ByVal left As LimitedInt, _      ByVal right As LimitedInt) As LimitedInt    Dim temp As Integer = left.Value * right.Value    Select Case temp      Case 1 To 10 : Return New LimitedInt(temp)      Case Else : Throw New OverflowException    End Select   End Operator    Public Shared Operator /(ByVal left As LimitedInt, _      ByVal right As LimitedInt) As Double    Return left.Value / right.Value   End Operator    Public Shared Operator \(ByVal left As LimitedInt, _      ByVal right As LimitedInt) As LimitedInt    Dim temp As Integer = left.Value \ right.Value    Select Case temp      Case 1 To 10 : Return New LimitedInt(temp)      Case Else : Throw New OverflowException    End Select   End Operator    Public Shared Operator Mod(ByVal left As LimitedInt, _      ByVal right As LimitedInt) As LimitedInt    Dim temp As Integer = left.Value Mod right.Value    Select Case temp      Case 1 To 10 : Return New LimitedInt(temp)      Case Else : Throw New OverflowException    End Select   End Operator    Public Shared Operator And(ByVal left As LimitedInt, _      ByVal right As LimitedInt) As LimitedInt    Dim temp As Integer = left.Value And right.Value    Select Case temp      Case 1 To 10 : Return New LimitedInt(temp)      Case Else : Throw New OverflowException    End Select   End Operator    Public Shared Operator Or(ByVal left As LimitedInt, _      ByVal right As LimitedInt) As LimitedInt    Dim temp As Integer = left.Value Or right.Value    Select Case temp      Case 1 To 10 : Return New LimitedInt(temp)      Case Else : Throw New OverflowException    End Select   End Operator    Public Shared Operator Xor(ByVal left As LimitedInt, _      ByVal right As LimitedInt) As LimitedInt    Dim temp As Integer = left.Value Xor right.Value    Select Case temp      Case 1 To 10 : Return New LimitedInt(temp)      Case Else : Throw New OverflowException    End Select   End Operator    Public Shared Operator ^(ByVal left As LimitedInt, _      ByVal right As LimitedInt) As Double    Return left.Value ^ right.Value   End Operator    Public Shared Operator <(ByVal left As LimitedInt, _      ByVal right As LimitedInt) As Boolean    Return left.Value < right.Value   End Operator    Public Shared Operator >(ByVal left As LimitedInt, _      ByVal right As LimitedInt) As Boolean    Return left.Value > right.Value   End Operator    Public Shared Operator <=(ByVal left As LimitedInt, _      ByVal right As LimitedInt) As Boolean    Return left.Value <= right.Value   End Operator    Public Shared Operator >=(ByVal left As LimitedInt, _      ByVal right As LimitedInt) As Boolean    Return left.Value >= right.Value   End Operator    Public Shared Widening Operator CType(ByVal left As LimitedInt) As Integer    Return left.Value   End Operator    Public Shared Narrowing Operator CType(ByVal left As Integer) As LimitedInt    Return New LimitedInt(left)   End Operator   End Structure