Importing C++ CLR wrapper DLL into Python

Question

Importing C++ CLR wrapper DLL into Python

JDias 136

I made a C++ CLR DLL (libwrapper.dll) that imports a C# DLL (lib2.dll):

include <stdio.h>

using "lib2.dll"

extern "C" __declspec(dllexport) int __cdecl getid() {
return (MyCls::getid());
}

This is a kind of hello world program...

Now from python, I do:

from ctypes import *

lib=WinDLL("./libwrapper.dll")
lib.getid.restype=c_int
lib.getid.argtypes=()

print(f"Id = {lib.getid()}")

obtaining the error (in the last line):

Traceback (most recent call last):
File "lw.py", line 7, in <module>
print(f"Id = {lib.getid()}")
OSError: [WinError -532462766] Windows Error 0xe0434352

How can I avoid this error? Is there anything wrong in the code?

What are the options for compiling libwrapper.dll? In the command-line I tried cl libwrapper.cpp /LD /CLR

Viorel 122.6K Reputation points

2021-01-12T16:25:39.107+00:00

Before experimenting with CLR, did you try a native (non-CLR) simple DLL?
RLWA32 49,536 Reputation points

2021-01-13T12:07:17.207+00:00

Is the C# class library (lib2.dll) in the same folder as the mixed-mode assembly (libwrapper.dll)?
JDias 136 Reputation points

2021-01-13T15:14:26.85+00:00

lib2.dll is made in C#, and of course all are in the same directory.

lib2.dll:

using System.Runtime.InteropServices;

public class MyCls
{
public static int getid()
{
return (101);
}
}

and was compiled with csc -target:library and may be easily imported with C++.
RLWA32 49,536 Reputation points

2021-01-13T17:36:22.387+00:00

I'm not a python user.

I tried simulating the environment with a C++ console application, a C++/CLI mixed mode assembly and a C# class library. In my quick and limited test the console application would load the mixed-mode assembly with LoadLibrary/GetProcAddress to obtain the exported function which calls a static method in the C# class library. What I noticed was that unless the C# class library was in the same folder as the console application (or in a properly named subfolder) an 0xE0434352 exception would be thrown.
JDias 136 Reputation points

2021-01-19T17:57:58.263+00:00

It's all in the same directory...

Do I have to use RegAsm or RegSvr32 utilities from Visual Studio? How? What should I do with my libwrapper.dll to run these?
JDias 136 Reputation points

2021-01-19T18:00:07.947+00:00

Yes, I tried.

I wrote a DLL in C++ and then I was able to run it with python, as with C++.

Please note that I'm using the command-line commands CL and CSC.
Viorel 122.6K Reputation points

2021-01-19T18:11:26.707+00:00

Did you try compiling this simple DLL with /CLR option, without adding C# module yet?
RLWA32 49,536 Reputation points

2021-01-19T18:28:00.557+00:00

As I understand it, unless your assemblies are in the GAC the CLR will search for them in the folder (or properly named subfolder) that contains the executable (.exe) that wants to load the assembly.

how-the-runtime-locates-assemblies
JDias 136 Reputation points

2021-01-20T14:17:18.25+00:00

The DLL lib2.dll was written in C# and compiled with CSC, while DLL libwrapper.dll was compiled with CL /CLR switch
JDias 136 Reputation points

2021-01-21T13:55:50.153+00:00

Yes, it is!

Your answer

Viorel 122.6K Reputation points

2021-01-12T16:25:39.107+00:00

Before experimenting with CLR, did you try a native (non-CLR) simple DLL?
RLWA32 49,536 Reputation points

2021-01-13T12:07:17.207+00:00

Is the C# class library (lib2.dll) in the same folder as the mixed-mode assembly (libwrapper.dll)?
JDias 136 Reputation points

2021-01-13T15:14:26.85+00:00

lib2.dll is made in C#, and of course all are in the same directory.

lib2.dll:

using System.Runtime.InteropServices;

public class MyCls
{
public static int getid()
{
return (101);
}
}

and was compiled with csc -target:library and may be easily imported with C++.
RLWA32 49,536 Reputation points

2021-01-13T17:36:22.387+00:00

I'm not a python user.

I tried simulating the environment with a C++ console application, a C++/CLI mixed mode assembly and a C# class library. In my quick and limited test the console application would load the mixed-mode assembly with LoadLibrary/GetProcAddress to obtain the exported function which calls a static method in the C# class library. What I noticed was that unless the C# class library was in the same folder as the console application (or in a properly named subfolder) an 0xE0434352 exception would be thrown.
JDias 136 Reputation points

2021-01-19T17:57:58.263+00:00

It's all in the same directory...

Do I have to use RegAsm or RegSvr32 utilities from Visual Studio? How? What should I do with my libwrapper.dll to run these?
JDias 136 Reputation points

2021-01-19T18:00:07.947+00:00

Yes, I tried.

I wrote a DLL in C++ and then I was able to run it with python, as with C++.

Please note that I'm using the command-line commands CL and CSC.
Viorel 122.6K Reputation points

2021-01-19T18:11:26.707+00:00

Did you try compiling this simple DLL with /CLR option, without adding C# module yet?
RLWA32 49,536 Reputation points

2021-01-19T18:28:00.557+00:00

As I understand it, unless your assemblies are in the GAC the CLR will search for them in the folder (or properly named subfolder) that contains the executable (.exe) that wants to load the assembly.

how-the-runtime-locates-assemblies
JDias 136 Reputation points

2021-01-20T14:17:18.25+00:00

The DLL lib2.dll was written in C# and compiled with CSC, while DLL libwrapper.dll was compiled with CL /CLR switch
JDias 136 Reputation points

2021-01-21T13:55:50.153+00:00

Yes, it is!

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Importing C++ CLR wrapper DLL into Python

include <stdio.h>

using "lib2.dll"

Your answer