How do I specify a validation requirement for users of my class?

Question

I am implementing a class that wraps around an XML document with a very strictly defined schema. I do not control the circuit.

One of the properties in the class is the value of the element, which indicates the scheme that must match a particular regular expression. In the installer for a property, if the string does not match the expression, I throw an exception.

My question is, how do I better tell users of my class the requirements for this field? Is there an attribute that I can use? Xml comments (how does this manifest in intellisense)? Should I do something other than an exception? What other options do I have?

Answer 1

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Answer 2

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Answer 3

XML . :

" <elementname> /regex/ ";

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Answer 4

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Answer 5

, , MatchedString . , :

Public Class MatchedString
    Public Enum InvalidValueBehaviors
        SetToEmpty
        AllowSetToInvalidValue
        DoNothing
    End Enum

    Public Sub New(ByVal Expression As String)
        Me.expression = Expression
        exp = New Regex(Me.expression)
    End Sub

    Public Sub New(ByVal Description As String, ByVal Expression As String)
        Me.expression = Expression
        exp = New Regex(Me.expression)
        _expressiondescription = Description
    End Sub

    Public Sub New(ByVal Expression As String, ByVal ThrowOnInvalidValue As Boolean, ByVal InvalidValueBehavior As InvalidValueBehaviors)
        Me.expression = Expression
        exp = New Regex(Me.expression)
        Me.ThrowOnInvalidValue = ThrowOnInvalidValue
        Me.InvalidValueBehavior = InvalidValueBehavior
    End Sub

    Public Sub New(ByVal Description As String, ByVal Expression As String, ByVal ThrowOnInvalidValue As Boolean, ByVal InvalidValueBehavior As InvalidValueBehaviors)
        Me.expression = Expression
        exp = New Regex(Me.expression)
        _expressiondescription = Description
        Me.ThrowOnInvalidValue = ThrowOnInvalidValue
        Me.InvalidValueBehavior = InvalidValueBehavior
    End Sub

    Private exp As Regex
    Private expression As String

    Public ReadOnly Property MatchExpression() As String
        Get
            Return expression
        End Get
    End Property

    Public ReadOnly Property ExpressionDescription() As String
        Get
            Return _expressiondescription
        End Get
    End Property
    Private _expressiondescription As String

    Public Function CheckIsMatch(ByVal s As String)
        Return exp.IsMatch(s)
    End Function

    Public Property ThrowOnInvalidValue() As Boolean
        Get
            Return _thrownoninvalidvalue
        End Get
        Set(ByVal value As Boolean)
            _thrownoninvalidvalue = value
        End Set
    End Property
    Private _thrownoninvalidvalue = True

    Public Property InvalidValueBehavior() As InvalidValueBehaviors
        Get
            Return _invalidvaluebehavior
        End Get
        Set(ByVal value As InvalidValueBehaviors)
            _invalidvaluebehavior = value
        End Set
    End Property
    Private _invalidvaluebehavior As InvalidValueBehaviors = InvalidValueBehaviors.DoNothing

    Public Property Value() As String
        Get
            Return _value
        End Get
        Set(ByVal value As String)
            If value Is Nothing Then value = "" 'Never set to Nothing

            If CheckIsMatch(value) Then
                _value = value
            Else
                Select Case InvalidValueBehavior
                    Case InvalidValueBehaviors.AllowSetToInvalidValue
                        _value = value
                    Case InvalidValueBehaviors.SetToEmpty
                        _value = ""
                End Select

                If ThrowOnInvalidValue Then
                    Throw New ArgumentOutOfRangeException(String.Format("String: {0} does not match expression: {1}", value, MatchExpression))
                End If
            End If
        End Set
    End Property
    Private _value As String = ""

    Public Overrides Function ToString() As String
        Return _value
    End Function
End Class