Is it possible to run a method by giving a it's name in string not by a referene?

Well that's basicaly it!

Yes, search the board for "Reflection".

The easiest way is to use the CallByName function.

I find out about more VB shortcuts in these forums!

In an effort to learn the underlying .Net way of doing things I've avoided the VisualBasic namespace as much as possible - perhaps this results in more work on my part, but it also gives a better understanding of whats actually going on. It would appear that the CallByName function wraps a number of reflection steps into a single call. Handy - but not very revealing.

Here is a simple example of using reflection to invoke a method on an object instance by method name.

First, assume the simple class Foo:

Code Snippet

Public Class Foo

Public Function HelloWorld1() As String

Return "Hello World - One"

End Function

Public Function HelloWorld2() As String

Return "Hello World - Two"

End Function

End Class

Now, with an instance of Foo created, here is the code to invoke a method by name on the instance:

Hope that helps!

Hi Antinsh,

Youcan pass string of method name to dynamically call method. We needto usethe Type.InvokeMember method. Here is a little example of what you are trying to do. Hope this helps.

Code Snippet

Yes, search the board for "Reflection".

Hi,

I have been looking at the following commands etcetera, some of which I am confused by ( I must admit ).>>

• AddHandler
• AddressOf
• WithEvents

I am not sure if one of them will also let you do what you are after doing?

Take a look at.>>

http://msdn2.microsoft.com/en-us/library/ms172880(VS.80).aspx

http://msdn2.microsoft.com/en-us/library/74wy9422(vs.80).aspx

http://msdn2.microsoft.com/en-us/library/stf7ebaz(vs.71).aspx

The only way I can see of doing it is to Call a Sub or Function based on the contents of the string.>>>>

Regards,

S_DS

The easiest way is to use the CallByName function.

I find out about more VB shortcuts in these forums!

In an effort to learn the underlying .Net way of doing things I've avoided the VisualBasic namespace as much as possible - perhaps this results in more work on my part, but it also gives a better understanding of whats actually going on. It would appear that the CallByName function wraps a number of reflection steps into a single call. Handy - but not very revealing.

Here is a simple example of using reflection to invoke a method on an object instance by method name.

First, assume the simple class Foo:

Code Snippet

Public Class Foo

Public Function HelloWorld1() As String

Return "Hello World - One"

End Function

Public Function HelloWorld2() As String

Return "Hello World - Two"

End Function

End Class

Now, with an instance of Foo created, here is the code to invoke a method by name on the instance:

Hope that helps!

Hi rkimble.

Public Class Form1

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

Dim f As New Foo

Dim methodName As String

Dim result As String = ""

methodName = "HelloWorld1"

result = GetType(Foo).GetMethod(methodName).Invoke(f, Nothing)

MessageBox.Show(result)

End Sub

End Class

Gives an "Object reference not set to an instance of an object" exception error in the highlighted line above.

Even with result as OBJECT.

Yes I did add your Foo CLASS code separately.

Regards,

S_DS

Hi SDS,

Please check your code - this error indicates that the Class Foo does not contain a method named "HelloWorld1". You must have made an error when adding the Foo class to the project...

The code example I posted is correct. You can change the reflection line to the following if you like:

This will get the value of the Text property on the current form (and prove that this reflection works).

Best regards,

-Reed

Hi Antinsh,

Youcan pass string of method name to dynamically call method. We needto usethe Type.InvokeMember method. Here is a little example of what you are trying to do. Hope this helps.

Code Snippet

Thanx for help

CallByName works just fine!

Now I'm looking for a way to get a reference to a control by giving it's name as a string. But thats in another thread!