VB6 Interop of Function with Array of User Defined Type (UDT)

27. January 2013 03:33 by Mrojas in   //  Tags: , , , , , , , , ,   //   Comments (0)

Well tonight while I was deleting some spam comments from my blog and watching Dr. Who with my wife, I found a rather interesting comment.

So the story was:

First there is a VB6 DLL that had a class called Class1 with code like the following:

public type emprecord 
name as string 
end type 

Public Sub Fn(T()as emprecord) 
 MsgBox "The silence is comming said Prisoner 0"
End Sub

When this little dll was called from a VB.NET big brother 

Dim test as new prj.class1   
Dim em(0) as prj.emprecord 'able to create it no problem 
test.fn(em)  ' here gives error

An error ocurred... well this is not very document issue with the TLBIMP tool which creates the interop assemblies. See StackOverflow Answer. The workaround is to right click on your type library, select properties, and change Embed interop Types to false.

After that you will be able to call your function.

Silverlight and what to do with Application or User Settings or INI files

Some people ofter forget about this (even me Confused smile ) So that;’s why I’m posting about this.

In my work (at Artinsoft) we are currently performing a lot of Winforms and VB6 
migration to Silverlight. And a common problem is “What can I do with the user settings!!!”.

In VB6 you had your INI files and in Winforms you probably used something like the App settings.
But when you move to Silverlight what can you do!.
You need a set of initial values and you probably wont want to “burn” those inicial values in your XAP file.
It would be nicer if those values can just be set in the Web.Config file.

So a common way to solve this, is develop a simple helper class. This helper class will use a service that will
collect your initial ini files or appsettings values and store them in your Isolated Storage.
You can even use some kind of basic cryptography if you feel that your date is sensitive.

And then you can use the helpful IsolatedStorageSettings class. For example see this code,
that I borrowed from this post: http://wildermuth.com/2008/10/21/Using_Isolated_Storage_Settings_in_Silverlight_2

const string FAVCOLORNAME = "favoriteColor";
public Color? FavoriteColor
    if (IsolatedStorageSettings.ApplicationSettings[FAVCOLORNAME] != null)
      Color? colorSetting =         IsolatedStorageSettings.ApplicationSettings[FAVCOLORNAME] as Color?;
      if (colorSetting != null) return colorSetting;

    // If we can't find a favorite color, return a null color
    return new Color?();
    IsolatedStorageSettings.ApplicationSettings[FAVCOLORNAME] = value;

As you can see is very easy to save and recover simple settings from the Silverlight Isolated Storage