How can I use textbox textchanged events to change user input classes? - vb.net

Question

InputValue1,..OperationAdd are instances of the class InputNumber. How do I assign my Inputvalues to the corresponding textboxes as option Strict On is activated?
Class MainWindow
Dim InputValue1 As New InputNumber
Dim InputValue2 As New InputNumber
Dim ExpectedResultValue As New InputNumber
Dim OperationAdd As New InputNumber
Private Sub TBoxNumber1_TextChanged(sender As Object, e As TextChangedEventArgs) Handles TBoxNumber1.TextChanged
TBoxNumber1.Text = InputValue1 'There is an error in this line, value of type InputNumber 'cannot be converted to a string
End Sub
Below is the InputNumber Class:
Public Class InputNumber
Inherits Input
Private _number As Integer
Public Property Number As Integer
Get
Return _number
End Get
Set(value As Integer)
_number = value
End Set
End Property
Protected Overrides Function Validate(s As String) As Boolean
Dim isValid As Boolean = Integer.TryParse(s, _number)
Return isValid
End Function
End Class

Answer 1

It seems to me that you should be getting the input from the TextBox into your InputNumber object, not the other way around. This:
TBoxNumber1.Text = InputValue1
should probably be this:
InputValue1.Validate(TBoxNumber1.Text)
When it actually comes time to display the value of that InputNumber, you would have to use InputValue1.Number.ToString(). Personally, I would add this to your InputNumber class:
Public Overrides Function ToString() As String
Return Number.ToString()
End Function
and then you can use InputValue1.ToString() instead.
EDIT:
It's been pointed out that the Validate method is Protected so it can't be called like that. Unless there's some use for it in the Input base class, I'm not sure what it's for because, as it stands, you'd need to validate externally anyway, e.g.
Dim number As Integer
If Integer.TryParse(TBoxNumber1.Text, number) Then
InputValue1.Number = number
End If

Answer 2

I am questioning the implementation of InputNumber. It does not make much sense in the current form. We don't know when validation is happen and Number is integer in fact.
I would do something like this.
Public Class InputNumber
Private _number As Integer
Private _hasNumber As Boolean
Public Sub New(s As String)
SetNumber(s)
End Sub
Public Sub New()
End Sub
Public ReadOnly Property Number As Integer
Get
Return _number
End Get
End Property
Public ReadOnly Property HasNumber As Boolean
Get
Return _hasNumber
End Get
End Property
Public Sub SetNumber(s As String)
_hasNumber = Integer.TryParse(s, _number)
End Sub
' For consistency...
Public Sub SetNumber(i As Integer)
_hasNumber = true
_number = i
End Sub
Public Overrides Function ToString() As String
If HasNumber Then Return Number.ToString()
Return String.Empty
End Function
End Class
Then your usage will be (and I agree with #jmcilhinney, when you have TextChange event, you want to take a value from the text box and set a variable)
Dim inp As New InputNumber("ddd")
txtBox1.Text = If(inp.HasNumber, inp.Number.ToString(), "NO VALUE") '' example to use HasNumber
inp.SetNumber("sss")
txtBox2.Text = inp.ToString() '' Example to use straight value
inp.SetNumber(10)
Dim current As Integer = If(inp.HasNumber, inp.Number, -1) '' using as numeric value
Now, this class makes slightly more sense