[IronPython] how to convert C# MarshalAs code to IronPython

[Curt Hagenlocher]

You'd need to decorate the string array parameter with a lot more
information -- it's an ANSI string rather than a Unicode string, for
instance, and there's another parameter that describes the length of the
array. But I just looked at the code for clrtype.accepts, and it doesn't
appear to support decorating the parameter types with additional attributes.
If you can get at the TypeBuilder -- and I know this used to be possible --
then the easiest way to implement this is probably just to call
TypeBuilder.DefinePInvokeMethod directly.


Is there a typo in the C# code? It looks like SizeParamIndex should be 1 and
not 10.

On Sat, Jun 5, 2010 at 10:57 PM, Ashley Abraham <abrahams84 at gmail.com>wrote:

> Hi,
>     I have the following C# code and I am trying to do the same
> functionality in IronPython, any help is appreciated.
>
> I was trying to do the same functionality in IronPython using the
> clrtype.py from the IronPython-2.6-Samples and I am able to connect to the
> library and the function but I am having trouble passing array of strings.
> With the current code it only passes the first letter and then it crashes.
>
> I am trying to call  cwavec(int, int, char *) and it is a C function which
> is part of the vniwave.dll and I am trying access it in IronPython.
>
> C# code:
>
> namespace PVWave
> {
>     public class OPI
>     {
>
> [DllImport("C:\\datk_code\\VNI\\wave\\bin\\bin.i386nt\\vniwave.dll",
>             EntryPoint = "cwavec",
>             ExactSpelling = false,
>             CharSet = CharSet.Ansi,
>             SetLastError = true)]
>         public static extern unsafe int cwavec(Int32 action, Int32 nCmds,
>             [MarshalAs(UnmanagedType.LPArray, ArraySubType =
> UnmanagedType.LPStr, SizeParamIndex = 10)] string[] cmds);
>
>     }
> }
>
> Here is my attempt in IronPython:
>
> import clrtype
> import System
> import sys
>
> class OPI(object):
>     "Description of Class"
>
>     # Note that you could also the "ctypes" modules instead of pinvoke
> declarations
>     __metaclass__ = clrtype.ClrClass
>
>     sys.path.append("C:\\datk_code\\VNI\\wave\\bin\\bin.i386nt")
>
>     from System.Runtime.InteropServices import DllImportAttribute,
> PreserveSigAttribute
>     DllImport = clrtype.attribute(DllImportAttribute)
>     PreserveSig = clrtype.attribute(PreserveSigAttribute)
>
>
>     @staticmethod
>     @DllImport("vniwave.dll")
>     @PreserveSig()
>     @clrtype.accepts(System.Int32, System.Int32,
> System.Array[System.String])
>     @clrtype.returns()
>     def cwavec(action, nCommands, commands): raise RuntimeError("this
> should not get called")
>
> def call_pinvoke_method_pvwave():
>     print "Calling pinvoke pvwave methods:"
>     actionNum = 2
>     nCommands = 1
>     commands = System.Array[System.String](['PRINT, "Connected to PV-Wave
> from IronPython"'])
>     print "cwavec(action, nCommands, commands):"
>     OPI.cwavec(actionNum, nCommands, commands)
>
> call_pinvoke_method_pvwave()
>
> Thanks
> Ash
>
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