Having problem with StructLayout & MarshalAs in Beta 2

[Patrick Ireland]

Well I finally got my SCSI DVD drive installed. Then I went through
the mental cruelity of install the Beta 2 on my WIN2K Pro system. Oh
happy thoughts 8-), let's jump right in and try to run one of my Beta 1
programs. What a cruel trick 8-(. The use of StructLayout and
MarshalAs now gives me compiler errors with code that worked in Beta 1.
I
guess that's why they call the blues (sorry, Beta). Any suggestions??

'
' Beta 2 documentation on structure definitions:
'

[ <attrlist> ] [{ Public | Protected | Friend | Protected Friend | Private
}] Structure name
[ variabledeclarations ]
[ proceduredeclarations ]
End Structure

'
' VB Program:
'

Imports System
Imports System.Text
Imports System.Console
Imports System.Runtime.InteropServices.StructLayoutAttribute

Module Module1
Sub Main()
End Sub
End Module

Public Class Class1
<StructLayout(LayoutKind.Sequential)> Public Structure Record1
Public Field1 As Integer
<MarshalAs(UnmanagedType.ByValArray, SizeConst:=8)> _
Public Field2 () As Byte
End Structure
End Class

'
'Works in Beta1
'
'Public Class Class1
' Public Structure <StructLayout(LayoutKind.Sequential)> Record1
' Public Field1 As Integer
' Public <MarshalAs(UnmanagedType.ByValArray, SizeConst:=8)> _
' Field2 () As Byte
' End Structure
'End Class
'

' Note:
' The ordering of the <StructLayout...> and <MarshalAs...> differ in
' what works in Beta1 and what the documentation states in Beta 2

[Mattias Sjögren]

Hi Patrick,

>Imports System
>Imports System.Text
>Imports System.Console
>Imports System.Runtime.InteropServices.StructLayoutAttribute

What you're missing is an Import for just the
System.Runtime.InteropServices namespace. Perhaps that's what you
wanted on the last line, because there's no reason that I can see to
Import StructLayoutAttribute (or any other attribute type).


Mattias

===
Mattias Sjögren (VB MVP)
mattias @ mvps.org
http://www.msjogren.net/dotnet/

[Patrick Ireland]

Mattias,

Thanks, that was a combination I had not tried yet and it does work.
Looking at the Beta1 vs Beta2 code, the order placement of the attribute
clause appears to have changed. Or I suffering under bleary eyed, fingers
typed to the bone delusions?

Code I used in Beta 1

Public Structure <StructLayout(LayoutKind.Sequential)> StrucName ...

whereas Beta 2 requires

<StructLayout(LayoutKind.Sequential)> Public Structure StrucName ...

mattias.dont.want.spam@mvps.org (Mattias Sjögren) wrote:
>Hi Patrick,
>
>>Imports System
>>Imports System.Text
>>Imports System.Console
>>Imports System.Runtime.InteropServices.StructLayoutAttribute
>
>What you're missing is an Import for just the
>System.Runtime.InteropServices namespace. Perhaps that's what you
>wanted on the last line, because there's no reason that I can see to
>Import StructLayoutAttribute (or any other attribute type).
>
>
>Mattias
>
>===
>Mattias Sjögren (VB MVP)
>mattias @ mvps.org
>http://www.msjogren.net/dotnet/

[Rob Teixeira]

"Patrick Ireland" <ireland@airmail.net> wrote:
>
>Mattias,
>
>Thanks, that was a combination I had not tried yet and it does work.
>Looking at the Beta1 vs Beta2 code, the order placement of the attribute
>clause appears to have changed. Or I suffering under bleary eyed, fingers
>typed to the bone delusions?
>

It has changed.
The attribute placement is more consistant now.

-Rob