how to sync the Culture of microsoft.visualbasic.compatibility.vb6.format with the application.currentCulture?

Question

Context: a program written in VB.NET, developed/maintained in VisualStudio2012, targeting framework v3.5.

A few years ago, the program was in VB(6) and we "translated" it to VB.NET. As a result of the transformation, which was mostly automated, we still have quite a few places in the code where formatting of doubles (and dates/...) for textual presentation is processed as in:

Dim sValue As String = Microsoft.VisualBasic.Compatibility.VB6.Format(dblValue, "0.00")

Conversely, when we need to extract a Double value from such a string, we use

Dim dblValue As Double = CDbl(sValue)

CDbl "listens to" the System.Globalization.CultureInfo.CurrentCulture of the applications Thread, and this does NOT change when - during the run of the code - you change the Regional Settings through the Control Panel.

However, the VB6.Format as executed in the code starts out conforming to the currentCulture of the application (as you might expect), BUT apparently (I didn't know this, but accidentally found out) listens to CHANGES in the Regional Settings and responds immediately to any changes you make there during the program execution. This implies that the CDbl() and VB6.Format() become mutually inconsistent.

Of course, changing the Regional Settings during program execution is awkward, and moreover, if you wish to support it, you can manage it by catching the SystemEvents.UserPreferenceChanged (and -Changing) events and act upon their occurrences.

However, the "different behaviour" of VB6.FORMAT versus "normal" casts as CDbl(someString) regarding changes in the Culture/Regional Settings, strikes me as undesirable. Preferably you would have VB6.Format to comply ALWAYS with the application/thread-CurrentCulture, and you may THEN choose how you want your code to respond to userpreference changes. Furthermore, I'd like to gain some more insight in the issue.

My question, therefore, is: Is there a way to compile/arrange/... things such that the (Microsoft.VisualBasic.Compatibility.)VB6.Format listens to the application-CurrentCulture and NOT respond - without "our consent" - to changes in Regional Settings?

Additional information: The program is compiled with - for the visualbasic stuff - a reference in the project (VisualStudio2012) to: C:\Windows\Microsoft.Net\Framework\V2.0.50727\Microsoft.VisualBasic.Compatibility.dll (and ...Data.dll).

Any "educational" information or suggestion is welcome. The issue is not causing any real problems in our program, but I feel that we should/might have a better understanding and maybe even methods to make things more robust.

Answer 1

The VB6 Format() function is actually an operating system function under the hood. VarFormat(), a function exported by oleaut32.dll. Backgrounder answer is here. The MSDN library article is here.

As you can tell from the MSDN article, the function doesn't permit specifying a culture or culture specific settings, other than the day-of-week rules. This function dates from 1996, life was much simpler back then. So what you see is now easy to explain, it cannot know anything about the .NET Thread.CurrentCulture setting.