run function from string

[=?Utf-8?B?SmFuIEhlcHBlbg==?=]

Hi,

I've a question. I'm developing a windows application and for the
application i need to run functions and procedures that are stored in a
database.
Here is an example that i tried to get working.
How can i execute the function that is stored in the string expr ?

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles Button1.Click
Dim expr As String = "test2(10,25)"
MessageBox.Show(expr)
expr.run()
End Sub
 
Function test2(ByVal i As Integer, ByVal x As Integer) As Boolean
Dim y As Integer
y = i + x
Return y
End Function
 

[Kevin Spencer]

You will have to write code that parses the text and calls the appropriate
function.

--
HTH,

Kevin Spencer
Microsoft MVP

Help test our new betas,
DSI PrintManager, Miradyne Component Libraries:
http://www.miradyne.net

"Jan Heppen" <Ja*******@disc ussions.microso ft.comwrote in message
news:D1******** *************** ***********@mic rosoft.com...

Hi,

I've a question. I'm developing a windows application and for the
application i need to run functions and procedures that are stored in a
database.
Here is an example that i tried to get working.
How can i execute the function that is stored in the string expr ?

   Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles Button1.Click
       Dim expr As String = "test2(10,25)"
       MessageBox.Show(expr)
       expr.run()
   End Sub

   Function test2(ByVal i As Integer, ByVal x As Integer) As Boolean
       Dim y As Integer
       y = i + x
       Return y
   End Function
 

[=?Utf-8?B?SmFuIEhlcHBlbg==?=]

Imports System.Text.Reg ularExpressions
Imports System.Reflecti on

Module Module1
Class Expression
Private Shared methodRegex As Regex = New
Regex("^(?<Meth od>\w[\w\d_]+)\s*(\((?<Para meters>.*)\))?$ ",
RegexOptions.Co mpiled Or RegexOptions.Si ngleline)
Public Shared Function Run(ByVal obj As Object, ByVal expr As
String) As Object
Dim m As Match = methodRegex.Mat ch(expr)
Dim method As String = m.Groups("Metho d").Value
Dim parameters As String = m.Groups("Param eters").Value
Dim params As Object() = Nothing

Dim binding As BindingFlags = BindingFlags.In vokeMethod Or
BindingFlags.In stance Or BindingFlags.St atic Or BindingFlags.Pu blic Or
BindingFlags.No nPublic

Dim mi As MethodInfo = obj.GetType().G etMethod(method , binding)

If mi Is Nothing Then
Return Nothing
End If

If Not String.IsNullOr Empty(parameter s) Then
Dim stringParams As String() = parameters.Spli t(New String()
{","}, StringSplitOpti ons.RemoveEmpty Entries)
ReDim params(stringPa rams.Length - 1)

Dim parameterInfo As ParameterInfo() = mi.GetParameter s()

If params.Length <parameterInfo. Length Then
Return Nothing
End If

For Each pi As ParameterInfo In parameterInfo
params(pi.Posit ion) =
Convert.ChangeT ype(stringParam s(pi.Position), pi.ParameterTyp e)
Next
End If

Return mi.Invoke(obj, binding, Nothing, params,
Threading.Threa d.CurrentThread .CurrentCulture )
End Function
End Class

Sub Main()
Dim expr As String = "test2(10,2 5)"
Expression.Run( New TestClass, expr)
End Sub

Class TestClass
Public Function test2(ByVal i As Integer, ByVal x As Integer) As
Integer
Dim y As Integer
y = i + x
Return y
End Function
End Class
End Module
"Jan Heppen" wrote:

Hi,

I've a question. I'm developing a windows application and for the
application i need to run functions and procedures that are stored in a
database.
Here is an example that i tried to get working.
How can i execute the function that is stored in the string expr ?

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles Button1.Click
        Dim expr As String = "test2(10,25)"
        MessageBox.Show(expr)
        expr.run()
    End Sub

    Function test2(ByVal i As Integer, ByVal x As Integer) As Boolean
        Dim y As Integer
        y = i + x
        Return y
    End Function
 

[Abdul Aleem]

I assume you already have the 'test2' function in the same class from where
you want to invoke it.
You can invoke the function in the expr as follows

Dim expr As String = "test2"

Dim obj As Object = Activator.Creat eInstance(Me.Ge tType(), New String() {})

Dim result As Object = Me.GetType.Invo keMember(expr,
Reflection.Bind ingFlags.Defaul t Or Reflection.Bind ingFlags.Invoke Method,
Nothing, Me, New Object() {10, 25})

MessageBox.Show (CType(result, Integer).ToStri ng())

Note that I have passed your parameters (10, 25) as the final parameter to
the InvokeMember function which is a param array. Also correct your test2
function, I think it is required to return an integer whereas the return
type is boolean.
--
Abdul Aleem
Blog: http://aleemkhan.wordpress.com

"Jan Heppen" <Ja*******@disc ussions.microso ft.comwrote in message
news:D1******** *************** ***********@mic rosoft.com...

Hi,

I've a question. I'm developing a windows application and for the
application i need to run functions and procedures that are stored in a
database.
Here is an example that i tried to get working.
How can i execute the function that is stored in the string expr ?

   Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles Button1.Click
       Dim expr As String = "test2(10,25)"
       MessageBox.Show(expr)
       expr.run()
   End Sub

   Function test2(ByVal i As Integer, ByVal x As Integer) As Boolean
       Dim y As Integer
       y = i + x
       Return y
   End Function