VB.NET implementation of DllImport from C#?

[Vagabond Software]

I am trying to convert a C# .NET wrapper for Microsoft's unmanaged
'cabinet.dll' to Visual Basic .NET and have hit a stumbling block. Here is
the C# code that I am trying to convert:

[DllImport("cabi net.dll",
CallingConventi on=CallingConve ntion.Cdecl,
EntryPoint="FDI Create")]
private static extern IntPtr FdiCreate(
FdiMemAllocDele gate fnMemAlloc,
FdiMemFreeDeleg ate fnMemFree,
FdiFileOpenDele gate fnFileOpen,
FdiFileReadDele gate fnFileRead,
FdiFileWriteDel egate fnFileWrite,
FdiFileCloseDel egate fnFileClose,
FdiFileSeekDele gate fnFileSeek,
int cpuType, // ignored by 32-bit FDI
[In, Out][MarshalAs(Unman agedType.LPStru ct)] CabError erf);

As you can see, this method is defined but without any '{}' brackets. It
also uses the C# 'extern' keyword. A method of the same name is then
declared publicly as follows:

public static IntPtr FdiCreate(
FdiMemAllocDele gate fnMemAlloc,
FdiMemFreeDeleg ate fnMemFree,
FdiFileOpenDele gate fnFileOpen,
FdiFileReadDele gate fnFileRead,
FdiFileWriteDel egate fnFileWrite,
FdiFileCloseDel egate fnFileClose,
FdiFileSeekDele gate fnFileSeek,
CabError erf)
{
return FdiCreate(fnMem Alloc, fnMemFree, fnFileOpen, fnFileRead,
fnFileWrite,
fnFileClose, fnFileSeek, cpuTypeUnknown, erf);
}

My attempt at the converting the first code snippet to VB.NET looks like
this:

<DllImport("cab inet.dll", CallingConventi on:=CallingConv ention.Cdecl, _
EntryPoint:="FD ICreate")> _
Private Shared Function FDICreate(ByVal pfnAlloc As FdiMemAllocDele gate, _
ByVal pfnFree As FdiMemFreeDeleg ate, _
ByVal pfnOpen As FdiFileOpenDele gate, _
ByVal pfnRead As FdiFileReadDele gate, _
ByVal pfnWrite As FdiFileWriteDel egate, _
ByVal pfnClose As FdiFileCloseDel egate, _
ByVal pfnSeek As FdiFileSeekDele gate, _
ByVal cpuType As Integer, <MarshalAs(Unma nagedType.LPStr uct)> _
ByRef perf As CabError) As IntPtr
End Function

Basically, I'm a little lost on the translation. Visual Studio seems to be
allowing me to create another 'Public' funciton named FDICreate, just like
in the C# version, but if there is a problem in my initial attempt at
conversion, I'd like a heads-up now.

Thanks in advance for any help.

Carl

[Tom Shelton]

Re: VB.NET implementation of DllImport from C#?

In article <#tNTckDyFHA.37 56@tk2msftngp13 .phx.gbl>, Vagabond Software wrote:[color=blue]
> I am trying to convert a C# .NET wrapper for Microsoft's unmanaged
> 'cabinet.dll' to Visual Basic .NET and have hit a stumbling block. Here is
> the C# code that I am trying to convert:
>
> [DllImport("cabi net.dll",
> CallingConventi on=CallingConve ntion.Cdecl,
> EntryPoint="FDI Create")]
> private static extern IntPtr FdiCreate(
> FdiMemAllocDele gate fnMemAlloc,
> FdiMemFreeDeleg ate fnMemFree,
> FdiFileOpenDele gate fnFileOpen,
> FdiFileReadDele gate fnFileRead,
> FdiFileWriteDel egate fnFileWrite,
> FdiFileCloseDel egate fnFileClose,
> FdiFileSeekDele gate fnFileSeek,
> int cpuType, // ignored by 32-bit FDI
> [In, Out][MarshalAs(Unman agedType.LPStru ct)] CabError erf);
>
> As you can see, this method is defined but without any '{}' brackets. It
> also uses the C# 'extern' keyword. A method of the same name is then
> declared publicly as follows:
>
> public static IntPtr FdiCreate(
> FdiMemAllocDele gate fnMemAlloc,
> FdiMemFreeDeleg ate fnMemFree,
> FdiFileOpenDele gate fnFileOpen,
> FdiFileReadDele gate fnFileRead,
> FdiFileWriteDel egate fnFileWrite,
> FdiFileCloseDel egate fnFileClose,
> FdiFileSeekDele gate fnFileSeek,
> CabError erf)
> {
> return FdiCreate(fnMem Alloc, fnMemFree, fnFileOpen, fnFileRead,
> fnFileWrite,
> fnFileClose, fnFileSeek, cpuTypeUnknown, erf);
> }
>
> My attempt at the converting the first code snippet to VB.NET looks like
> this:
>
><DllImport("ca binet.dll", CallingConventi on:=CallingConv ention.Cdecl, _
> EntryPoint:="FD ICreate")> _
> Private Shared Function FDICreate(ByVal pfnAlloc As FdiMemAllocDele gate, _
> ByVal pfnFree As FdiMemFreeDeleg ate, _
> ByVal pfnOpen As FdiFileOpenDele gate, _
> ByVal pfnRead As FdiFileReadDele gate, _
> ByVal pfnWrite As FdiFileWriteDel egate, _
> ByVal pfnClose As FdiFileCloseDel egate, _
> ByVal pfnSeek As FdiFileSeekDele gate, _
> ByVal cpuType As Integer, <MarshalAs(Unma nagedType.LPStr uct)> _
> ByRef perf As CabError) As IntPtr
> End Function
>
> Basically, I'm a little lost on the translation. Visual Studio seems to be
> allowing me to create another 'Public' funciton named FDICreate, just like
> in the C# version, but if there is a problem in my initial attempt at
> conversion, I'd like a heads-up now.
>
> Thanks in advance for any help.
>
> Carl
>
>[/color]

Quick glance, and with out the definitions of the delegates/structs - it
looks ok. The only real comment I have is that the
MashalAs(Unmana gedType.LPStruc t) is probably unnecessary (in both
versions actually).

--
Tom Shelton