GURUS: VB .NET alternatives to C# type conversion operators and operator overloading?

[Krunoslav]

Hi ,

I have implemented a struct in C# which acts as a sort of a variant type,
i.e
its constructors accept numeric types, dates and strings and the struct
itself
is convertible to those types but no other types and can perform arithmetic
operations with those types too.

But arithmetic operations are not as important to me as the seamless
conversion to and fro.

For the conversion purpose I had to implement static conversion operators,
implicit and explicit.
I also implemented IConvertible interface in the struct.

NOW THE PROBLEM.
After testing the class in VB .NET I realized that those static converters
as well as any static operators are unavailable. In C# everything works
fine, but
in VB I could not say something like

MyStruct = 100
or MyStruct = CType(100, MyStruct)
even though MyStruct has a constructor with an int value (and others) as
well as the conversion operators.

Examination of my objects with ildasm proves that all of the conversion
operators are there.
As I say in C# everything works perfectly as it should.

So I considered implementing a custom TypeConverter for my struct to see if
this will help.

Then I performed the test in VB .NET to see what I can do with just the VB
..NET itself not C#.

I wrote the following in VB as a test, just the constructors and the
TypeConverter:
I implemented a type converter SmartTypeConverter for the structure too.

namespace test
<TypeConverter(GetType(SmartTypeConverter))> _
Public Structure VBSmartVar
Private m_object As Object

Public Sub New(ByVal v As String)
m_object = New Object()
m_object = v
End Sub

Public Sub New(ByVal v As Integer)
m_object = New Integer()
m_object = v
End Sub

Public Sub New(ByVal v As Double)
m_object = New Double()
m_object = v
End Sub

Public Overrides Function ToString() As String
Return CStr(m_object)
End Function

Public Overloads Function GetTypeCode() As TypeCode
If TypeOf m_object Is String Then
Return CStr(m_object).GetTypeCode()
End If
If TypeOf m_object Is Integer Then
Return CInt(m_object).GetTypeCode()
End If
If TypeOf m_object Is Double Then
Return CDbl(m_object).GetTypeCode()
End If
End Function

Public Overloads Function GetHashCode() As Integer
If TypeOf m_object Is String Then
Return CStr(m_object).GetHashCode()
End If
If TypeOf m_object Is Integer Then
Return CInt(m_object).GetHashCode()
End If
If TypeOf m_object Is Double Then
Return CDbl(m_object).GetHashCode()
End If
End Function

End Structure
End Namespace

The test proved unsuccessful, I still can not say either
MyStruct = 100
or CType(100, MyStruct).

What I would like is something like this
MyStruct1 = 100
MyStruct2 = 100.45

MyInteger = CInt(MyStruct)
MyDouble = CDbl(MyStruct)

etc

I do not include here a type converter I used for brevity, but it implements
CanConvertTo, CanConvertFrom, ConvertTo, ConvertFrom and IsValid.

Is it POSSIBLE to do something like this in VB like it is in C# and if so
how please?
This issue may severely affect my entire system design construct from ground
up.

As you can see, I am more comfortable with C# due to a C++ background though
I used to program simple apps in VB 6. So if anyone knows a simple way to do
this in both C# and
VB please let me know.
Thanks to anyone that gives me any meaningful tips.

my email: (e-mail address removed).

 

[Tom]

Ah, welcome to my world. On this one feature many o' VB developers switched
to C#. The unfortunate answer if that there is no *neat* way for VB
developers to use conversion (or operator) overloads. For conversion
overloads, they can, of course, explicitedly cast their objects to the
appropriate type. For operator overloads they would need to Operator+
syntax.

You have come across one of the top reasons that C# is significantly better
than current version of VB.NET and why I personally see no reason to use the
current version of VB.NET.




Tom