Pythonnet: C# .NET windows form example with python calls

[tarpista]

I would like to ask that would it be possible to have an example .NET winform application which imports some python module, (ie numpy) and makes some call from it? I could not realy find such anywhere, and my trial fails right at the begining with

An unhandled exception of type 'System.ArgumentNullException' occurred in mscorlib.dll

Additional information: Value cannot be null.

Here is my code:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using Python.Runtime;

public partial class frmMain : Form
{
    public frmMain()
    {
        InitializeComponent();

        PythonEngine.Initialize(); //<- Error occurs here.
    }
}

Error details:

[denfromufa]

Well, you need to provide more info: Python, .NET, Windows versions and bitness. Is Python registered in %path%? Did you set any environment variables such as PYTHONPATH or PYTHONHOME?

Also look at troubleshooting wiki.

[tarpista]

I have several versions of pythons on my machine, my main goal was to be able to use one of my conda virtual environments (C:\PythonEnvs\NNDLM_conda) which has version "Python 2.7.13 :: Continuum Analytics, Inc."

If I check the registry entry for .NET version in .../NET Framework Setup/NDP/v4/Full there I have Version = 4.6.01055

I am using Win7 Pro 64 bit. Python is not registered in the path. Unfortunately I could not find any description about which python directory (and how) I should register from the followings I have:

C:\Python27\
C:\Python35\
C:\Miniconda3\
C:\PythonEnvs\NNDLM_conda\

The above error rises when the referenced dll is the one extracted from "pythonnet-2.0-Beta0-clr4.0_140_py27_UCS2_x86.zip".

At my first trial the Python.Runtime.dll was able to be built by using the "python setup.py build_ext --inplace" command, but that one could not be imported by Visual Studio for some reason that I dont remember. Thats why I thought to get an already built dll.

But now something might have changed on my computer, because if I run the "python setup.py build_ext --inplace" command again it gives an error:
error CS0656: Missing compiler required member 'Microsoft.CSharp.RuntimeBinder.CSharpArgumentInfo.Create'

Further on, if I create an environment variable called "PYTHONPATH", with the values of
"C:\Python27;C:\Python27\DLLs;C:\Python27\Lib;C:\Python27\Lib\lib-tk;C:\Python27\Lib\site-packages;"
or
"C:\PythonEnvs\NNDLM_conda;C:\PythonEnvs\NNDLM_conda\DLLs;C:\PythonEnvs\NNDLM_conda\Lib;C:\PythonEnvs\NNDLM_conda\Lib\lib-tk;C:\PythonEnvs\NNDLM_conda\Lib\site-packages;"
the building process fails in either cases with the following error:

Fatal Python error: Py_Initialize: unable to load the file system codec
File "C:\Python27\Lib\encodings__init__.py", line 123
raise CodecRegistryError,\
^
SyntaxError: invalid syntax

Current thread 0x00002528 (most recent call first):

and npython.exe just stops working.

Sorry for too long description, I am very new to python... When I found pythonnet I got very happy, I thought this time it became quite general that .net developers still make their guis in C# and do/call their calculations in/from python, but now I am getting the feeling it is only me who wants to use pythonnet in this direction... maybe I will also need fully turn toward python... Anyway, thanks for any help!

[denfromufa]

If you are new to Python, then please only install one version of Python
and work with it.

Using multiple versions of Python on one machine requires a very careful
setup.

Did you go through troubleshooting wiki?

On Mon, Jan 9, 2017, 7:50 AM tarpista [e-mail] wrote:

I have several versions of pythons on my machine, my main goal was to be
able to use ony of my conda virtual environments
(C:\PythonEnvs\NNDLM_conda) which has version "Python 2.7.13 :: Continuum
Analytics, Inc."

If I check the registry entry for .NET version in .../NET Framework
Setup/NDP/v4/Full there I have Version = 4.6.01055

I am using Win7 Pro 64 bit. Python is not registered in the path.
Unfortunately I could not find any description about which python directory
(and how) I should register from the followings I have:

C:\Python27
C:\Python35
C:\Miniconda3
C:\PythonEnvs\NNDLM_conda\

The above error rises when the referenced dll is the one extracted from
"pythonnet-2.0-Beta0-clr4.0_140_py27_UCS2_x86.zip".

At my first trial the Python.Runtime.dll was able to be built by using the
"python setup.py build_ext --inplace" command, but that one could not be
imported by Visual Studio for some reason that I dont remember. Thats why I
thought to get an already built dll.

But now something might have changed on my computer, because if I run the
"python setup.py build_ext --inplace" command again it gives an error:
error CS0656: Missing compiler required member
'Microsoft.CSharp.RuntimeBinder.CSharpArgumentInfo.Create'

Further on, if I create an environment variable called "PYTHONPATH", with
the values of

"C:\Python27;C:\Python27\DLLs;C:\Python27\Lib;C:\Python27\Lib\lib-tk;C:\Python27\Lib\site-packages;"
or

"C:\PythonEnvs\NNDLM_conda;C:\PythonEnvs\NNDLM_conda\DLLs;C:\PythonEnvs\NNDLM_conda\Lib;C:\PythonEnvs\NNDLM_conda\Lib\lib-tk;C:\PythonEnvs\NNDLM_conda\Lib\site-packages;"
the building process fails in either cases with the following error:

Fatal Python error: Py_Initialize: unable to load the file system codec
File "C:\Python27\Lib\encodings_init_.py", line 123
raise CodecRegistryError,
^
SyntaxError: invalid syntax

Current thread 0x00002528 (most recent call first):

and npython.exe just stops working.

Sorry for too long description, I am very new to python... When I found
pythonnet I got very happy, I thought this time it became quite general
that .net developers still make their guis in C# and do/call their
calculations in/from python, but now I am getting the feeling it is only me
who wants to use pythonnet in this direction... maybe I will also need
fully turn toward python... Anyway, thanks for any help!

—
You are receiving this because you commented.

Reply to this email directly, view it on GitHub
https://github.com/pythonnet/pythonnet/issues/318#issuecomment-271288521,
or mute the thread
https://github.com/notifications/unsubscribe-auth/AHgZ5XppabBRGsiskhv1HozqS6q2TaOGks5rQjsHgaJpZM4Ld0Tc
.

[JimSEOW]

I had similar problem and the wiki does not help me when I get stuck at

PythonEngine.Initialize(); //<- Error occurs here.

Could not load file or assembly 'Python.Runtime, Version=4.0.0.1, Culture=neutral, PublicKeyToken=null' or one of its dependencies

Looking at this does not suggest a way to debug

Building via setup.py will also copy the various output dlls into the correct place

I already check that all the output dlls are in the right place, yet I am not sure how/why the Python.Runtime needs for it to properly Initialize().

=> Perhaps someone can explain WHAT ARE THE STEPS involved in the initialize() step. What could cause the step to fail.

A straight forwards download and run simple example on how to embed will really help to debug how the python environment causes the error above.

FYI: I have no problem getting python to display a winForm, but how to embed as discussed above.

[tarpista]

Yes, I checked troubleshooting wiki, but could not succeed with it. Finally I found a workaround by using pythonnet in the other direction (as almost everyone does.), ie making .NET calls from python.

Basically now I make my gui in .NET (C#), and import it in python.
In example my C# code looks like this:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Threading;

namespace NeuralNetsGUI
{
    public partial class frmMain : Form
    {
        public Action fp_btn_LoadData_Click;

        public frmMain()
        {
            InitializeComponent();
        }

        private void btn_LoadData_Click(object sender, EventArgs e)
        {
            if (fp_btn_LoadData_Click != null)
            {
                new Thread(new ThreadStart(fp_btn_LoadData_Click)).Start(); //Asynchronus call
                //fp_btn_LoadData_Click.DynamicInvoke(); //Synchronous call
            }
        }
    }
}

As a post-build event in Visual Studio, I copy the compiled NeuralNetsGUI.exe file into my python directory, so it is possible to import it in python:

import clr
clr.AddReference("System.Windows.Forms")
clr.AddReference("NeuralNetsGUI") 

import System.Windows.Forms as WinForms
import NeuralNetsGUI as NetsGUI
from System import Action


class clsNetsGUI():
    """A class that creates windows form by importing NetsGUI.frmMain()"""

    def __init__(self):
        self.MainForm = NetsGUI.frmMain()
        self.MainForm.fp_btn_LoadData_Click = (Action(self.btn_LoadData_Click)) # <-- this is where I set the event handler function 

        app = WinForms.Application
        app.Run(self.MainForm)

    def btn_LoadData_Click(self):
        """Button click event handler"""
        print("Button clicked!")

def main():
    netsgui = clsNetsGUI()


if __name__ == '__main__':
    main()

[tarpista]

I got the solution for the initialization error. I was trying with a different version of Python.Runtime.dll which I got from somewhere else, because the pythonnet solution did not build for me.

Though it wasnt a good idea to do that. Instead I had to make the solution to build. By default it wants to build using mono, but on a windows machine you have to choose DebugWin and x86, that way it should build and work properly.

Another thread about it:
http://stackoverflow.com/questions/11443550/python-net-unable-to-load-python27-dll-with-winforms-but-console-application-wo

[denfromufa]

Have you really looked at this?

https://github.com/pythonnet/pythonnet/wiki/Troubleshooting-on-Windows-and-Linux

On Wed, Feb 1, 2017, 8:39 AM tarpista [e-mail] wrote:

Closed #318 https://github.com/pythonnet/pythonnet/issues/318.

—
You are receiving this because you commented.

Reply to this email directly, view it on GitHub
https://github.com/pythonnet/pythonnet/issues/318#event-944838170, or mute
the thread
https://github.com/notifications/unsubscribe-auth/AHgZ5dCuN6BkxdgErOP4R6kj0G78CtTwks5rYJk5gaJpZM4Ld0Tc
.

[tarpista]

Sure, but it did not help me out.

Actually I realized, that different versions of the Python.Runtime.dll are neccessary for me to let it work.

For the python -> C# direction the pip install pythonnet gets the proper Python.Runtime.dll and clr.pyd files for me.

But for the other direction, C# -> python I have to build the pythonnet solution to have the proper Python.Runtime.dll which can be referenced in a C# project.

This way I got both direction to work, but the dlls are different and only work in one direction, they are not interchangeable!! I mean if I 'copy clr.pyd and Python.Runtime.DLL to PYTHONFOLDER\Lib\site-packages\ or include their location path to search paths' the first direction will not work. Neither if I reference to the piped dll the second direction will fail....

[denfromufa]

Are you using the same CPython runtime in both cases? If yes, then you should not need 2 different Python.Runtime.DLL.

I'm guessing the issue is the key used to sign the Python.Runtime.DLL to get the strong name.

Can you please confirm that?

[tarpista]

Ah, thanks! You are right. Now it works with one and the same dll. I just went to C:\Python27\Scripts\ and typed pip install pythonnet which downloaded the clr.pyd and Python.Runtime.dll into C:\Python27\Lib\site-packages\ directory.

For the python project I set the environment location to C:\Python27\.

For the C# project I added a reference to the C:\Python27\Lib\site-packages\Python.Runtime.dll.

And it simply works.

So basically there was no need to build the solution, that caused me such a confusion. Do you think there are some cases when the above pip install does not work?

Please correct me that my understanding is correct. Since in a C# application it is not possible to set python environment, is the environment set explicitly by adding the reference to the proper Python.Runtime.dll at the proper location (..\Lib\site-packages\Python.Runtime.dll)?