[Python.NET] how to load and execute py file which consumes a thrid part C-based python extension in C# code

[lizy10b]

Thanks for your code, Bradley

I followed your sample,  add the path first , then  PythonEngine.ImportModule,
spending all the day in embeding the third part C-based library into my C# code, but PythonEngine.ImportModule still return Null.
I wrote a simple test C dll (only one function returns a+1), and a wrapper py file using the ctypes.
Then load the py file in C#, the PythonEngine.ImportModule does return a non-null value, but when invoke the function is saids can not find the dll. When I put the dll in the Python root dir (on my end is C:\Python262\) , the py file runs smoothly. I try to add the path of the dll into sys.path, but does not work, only putting it into the Python root dir works.

So I think the situation is: third part C-base python library (in my case, rtree and psycopg2) uses more complex ctypes warpper, so maybe the python.net is incomptible to it?  or I still have some chance to make it work, maybe still the sys.path problem?

Thanks

Zhiyu Li
                                 


2013-03-29 



lizy10b 



发件人： brad at fie.us 
发送时间： 2013-03-29  06:03:32 
收件人： lizy10b 
抄送： pythondotnet 
主题： Re: [Python.NET] how to load and execute py file which consumes a thrid part C-based python extension in C# code 
 
Sorry.  One more.


When my code then executes those callbacks, back into Python, it does so this way:


            System.Console.WriteLine("Getting Projects");
            List<libcontextutilsclient.ProjectContextSettings> ret = new List<libcontextutilsclient.ProjectContextSettings>(); //the things I expect python to give me back
            System.Console.WriteLine("Getting lock");
            IntPtr p = this.Pedestal.GetPythonLock();
            System.Console.WriteLine("Got Lock");
            if (this.ProjectsRequested != null)
            {
                foreach (libcontextutils.GetProjectSettingsDelegate del in this.ProjectsRequested.GetInvocationList())  //looping through callbacks on delegate
                {
                    System.Console.WriteLine("Calling Project Delegate");
                    ret.AddRange(del(projectsType, this));  //doing the callback, which is a python callback in truth.
                }
            }
            else
            {
                System.Console.Error.WriteLine("No delegates registered to ProjectsRequested Event.");
            }
            System.Console.WriteLine("Releasing lock");
            this.Pedestal.ReleasePythonLock(p);
            System.Console.WriteLine("Released Lock");
            return ret;



On Mar 28, 2013, at 5:34 PM, "brad at fie.us" <brad at fie.us> wrote:


In my code I'm running:


                Python.Runtime.PythonEngine.Initialize();



I also have these defined:


        public void AddPythonPath(string path)
        {
            CheckInitPython();
            IntPtr l = Python.Runtime.PythonEngine.AcquireLock();
            Python.Runtime.PythonEngine.RunSimpleString("import sys");
            Python.Runtime.PythonEngine.RunSimpleString("sys.path.append(\"" + path.Replace("\\", "\\\\") + "\")");
            Python.Runtime.PythonEngine.ReleaseLock(l);
        }

        public Python.Runtime.PyObject ImportModule(string name)
        {
            CheckInitPython();
            IntPtr l = Python.Runtime.PythonEngine.AcquireLock();
            Python.Runtime.PyObject module = Python.Runtime.PythonEngine.ImportModule(name);
            Python.Runtime.PythonEngine.ReleaseLock(l);
            if (module == null)
            {
                throw new libscclient.PythonModuleNotCreatedException(name);
            }
            return module;
        }



And when my code loads a "plugin" python module, it runs this:


            string pythonVersionBasePath = GetPythonCodeBaseVersionPath(); //my dynamic plugin code.
            string scriptName = GetPythonScriptName(); //also my dynamic plugin code.
            System.Console.WriteLine("importing module"); 
            Pedestal.AddPythonPath(pythonVersionBasePath); //calling code above
            Python.Runtime.PyObject module = Pedestal.ImportModule(scriptName.Split(new char[] { '.' }, 2)[0]);  //calling code above
            System.Console.WriteLine("module imported");
            IntPtr l = Pedestal.GetPythonLock();
            module.InvokeMethod(GetPythonInitMethodName(), new Python.Runtime.PyObject[] { Python.Runtime.PyObject.FromManagedObject(this) }); //calling a method by name.  the name comes from my dynamic plugin code.
            module.Dispose(); //I'm done with the module so I toss it.  my code here registers callbacks.
            Pedestal.ReleasePythonLock(l);



On Mar 28, 2013, at 2:09 PM, "lizy10b" <lizy10b at 126.com> wrote:


Thank you, Bradley.
I found a simple sample code on the maillist. Now I could load and execute a pure python function in a py file in C#. 

And a new problem is that the PythonEngine.ImportModule("modulename") method always return NULL in my case. The modulename.py comsumes a third part ctypes wrapped library (the Rtree 0.7 python library). It seems the PythonEngine can not find it, but actually it has been installed to the default path (C:\Python262\Lib\site-packages\rtree) , and the modulename.py file runs smoothly under python command line.
I worte a new py file which only contains a function returning the sys.path, and load it in C#, the sys.path seems OK.
So I don't know what's wrong....

Thanks.

Zhiyu Li




2013-03-29



lizy10b



发件人： Bradley Friedman
发送时间： 2013-03-28  22:15:18
收件人： lizy10b
抄送： pythondotnet
主题： Re: [Python.NET] how to load and execute py file which consumes a thrid part C-based python extension in C# code
What you are looking to do is "embed" a python interpreter in your .net project, using pythonnet, and then tell the runtime to execute your python script. 


I have done this in one of my projects. It does work. 


http://pythonnet.sourceforge.net/readme.html#embedding

Sent from my iPad

On Mar 28, 2013, at 8:31 AM, "lizy10b" <lizy10b at 126.com> wrote:


Hi there,
   I am a freshman and new to python.net.
I have a *.py script which calls a third part python library, and the library is a ctypes python wrapper of a C++ dll (or say C-based python extension?).
Frist I tried to make it using IronPython. IronPython works well when I load a pure python *.py (no third part libraries) file and execute it in C# code.
But it failed when I load a *.py which comsumes a thrid part ctypes python wrapper library mentioned above.

Then I turn to python.net. But I don't know how to load and execute *.py in C# code using python.net.

Thanks.

Zhiyu Li
Student
China

2013-03-28



lizy10b
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