Function delegate from a procedure address

[Bucky]

I've been trying to replicate some C++ code in VB.NET. The

C++ code gets a function address by using GetProcAddress, then

casts that into a delegate that then calls a callback function in

the code. So far I can correctly get the procedure address into

an IntPtr variable, but now I'm trying to create an instance of a

function delegate based on this address. DirectCast won't take

a value type (the procedure address) as a first parameter, so how

else might I cast it? The solution may lie in the Marshal object,

but I cannot find it.

 

Here's the C++ code:

// Here's the delegate declaration
typedef ULONG (*GetAttachedDevicesProc) (ULONG* pDeviceCount, PTCHAR pBuffer, ULONG* pBufferSize);

// And the instance of that delegate
static GetAttachedDevicesProc	 gGetAttachedDevices;

// This is the tricky part, it casts the proc address to an actual delegate
gGetAttachedDevices = (GetAttachedDevicesProc) ::GetProcAddress (fgUSBLib, "PalmUsbGetAttachedDevices")

 

And the VB.NET code I have so far:

' The delegate:
Private Delegate Function GetAttachedDevicesDelegate(ByVal deviceCount As Integer, ByVal buffer As String, ByVal bufferSize As Integer) As Integer

' Getting the procedure address:
procAddress = New IntPtr(GetProcAddress(moduleHandle.ToInt32(), "PalmUsbGetAttachedDevices"))

' Now how do I make a new instance of GetAttachedDevicesDelegate based on the address?

[Volte]

Perhaps you should make the return type of 'GetProcAddress' a Delegate type.

[Bucky]

Oooh, good idea... unfortunately it didn't work. An error was thrown:

"System.ArgumentException - Function pointer was not created

by a Delegate."

 

So it looks like it's closer than before...

[Volte]

Try here: http://staff.develop.com/woodring/dotnet/#getprocaddress