[Python.NET] Could you tell me how to call python from c#?

Barrett, Joey Joey.Barrett at itg.com
Thu Jun 7 20:09:10 CEST 2007


Yay!  Success!  Karpenstein, the details of PythonException really
helped me sort importing out.  THANK YOU SO MUCH!

Locally, everything works great---but when the project is deployed to
another environment it breaks.

The bin of my project contains:

Python.Runtime.dll
python24.dll

The deployed environment is installed with the same python as locally in
addition 'python' is in the path.

PythonEngine.Initialize();

Causes:  "Unable to load one or more of the requested types."


What am I missing?  How do you package up Python for .net appropriately?

Thanks in advance,

Joey J. Barrett
Investment Technology Group, Inc.
 

-----Original Message-----
From: Karpenstein, Nissim (C-BASS)
[mailto:Nissim.Karpenstein at C-BASS.COM] 
Sent: Thursday, June 07, 2007 6:08 AM
To: Barrett, Joey; Michael Eddington; pythondotnet at python.org
Subject: RE: [Python.NET] Could you tell me how to call python from c#?

Those numbers in your exception message are pointers to Python Strings
in the unmanaged side.  Use this:

      catch (PythonException ex)
      {
        String typ = new PyObject(ex.Type).ToString();
        String val = new PyObject(ex.Value).ToString();
        String trace = new PyObject(ex.Traceback).ToString();
        MessageBox.Show(typ + "\n" + val + "\n" + trace);
      }

I'm not sure of the answer to any of your other questions. 

> -----Original Message-----
> From: Barrett, Joey [mailto:Joey.Barrett at itg.com] 
> Sent: Wednesday, June 06, 2007 9:48 PM
> To: Karpenstein, Nissim (C-BASS); Michael Eddington; 
> pythondotnet at python.org
> Subject: RE: [Python.NET] Could you tell me how to call 
> python from c#?
> 
> Thanks for working through this with me.  Lots of questions, 
> but I promise to write a nice HOW-TO on all this once I get 
> it working from .NET.
> 
> ...
> if (module == null)
> {
> 	throw new PythonException();
> }
> catch (PythonException e)
> {
> 	result += e.Message + "\n" + e.StackTrace + "\n" + e.Type + "\n"
> + 		e.Value + e.Traceback;
> }
> 
> result.toString() yields:
> 
> Exception of type 'Python.Runtime.PythonException' was thrown. at
> PythonTester.PythonTest2() in C:\Documents and 
> Settings\user\workspace\PythonTester.cs:line 180 75319696
> 7542755275491888
> 
> 1.  How do I get the error from the interpreter?  (NOTE: I am 
> not "finalizing/shutting-down" the interpreter so the errors should be
> available)
> 
> 
> From a thread titled "[Python.NET] embedding in aspx problem"
> (http://mail.python.org/pipermail/pythondotnet/2004-May/000154.html),
> the user fixed the problem by adding a fully qualified path 
> to the sys.path.
> 
> My sys.path:
> 
> 'C:\\Documents and
> Settings\\jbarrett\\Desktop\\Kryptonite\\Kryptonite\\bin\\pyth
> on23.zip',
> '.\\DLLs', '.\\lib', '.\\lib\\plat-win', '.\\lib\\lib-tk', 
> 'C:\\WINDOWS\\Microsoft.NET\\Framework\\v2.0.50727'
> 
> 2.  What is python23.zip?  I don't see it anywhere.
> 
> 3.  Are the relative paths (ie. '.\\DLLs', '.\\lib', ...) 
> supposed to live off the root of the interpreter?
> 
> 4.  What is 
> 'C:\\WINDOWS\\Microsoft.NET\\Framework\\v2.0.50727' on the path for?
> 
> Thanks again for any help you can offer.
> 
> Joey J. Barrett
> Investment Technology Group, Inc.
> 
>  
> 
> -----Original Message-----
> From: Karpenstein, Nissim (C-BASS)
> [mailto:Nissim.Karpenstein at C-BASS.COM]
> Sent: Wednesday, June 06, 2007 12:10 PM
> To: Barrett, Joey; Michael Eddington; pythondotnet at python.org
> Subject: RE: [Python.NET] Could you tell me how to call 
> python from c#?
> 
> You can get the error message from ImportModule like this:
> 
> // After ImportModule
> if (module == null)
>   throw new PythonException()
> 
> That will check the error codes from the Python Interpreter 
> and populate fields in the Exception.
> The python interpreter being executed is the .dll version 
> probably in your windows\system32 directory.
> 
> I would try first to get the environemtn working the same 
> outside of vs.net.  Add c:\test to your pythonpath and make 
> sure you can call the method from the python prompt in a 
> shell window.  Then, if that's working, restart your vs and 
> it should work.  I'm not sure how to modify the pythonpath on 
> the fly or if that's really the problem.
> 
> 
> 
> > -----Original Message-----
> > From: Barrett, Joey [mailto:Joey.Barrett at itg.com]
> > Sent: Wednesday, June 06, 2007 3:02 PM
> > To: Michael Eddington; Karpenstein, Nissim (C-BASS); 
> > pythondotnet at python.org
> > Subject: RE: [Python.NET] Could you tell me how to call python from 
> > c#?
> > 
> > Thank you for all the help.
> > 
> > Loading a module located at C:\test\testModule.py is causing the 
> > following error: "Object reference not set to an instance of an 
> > object."
> > 
> > TestModule.py
> > 
> > def testMethod(self, options = {}):
> > 	m = {}
> > 	return m
> > 
> > 
> > The last line of this code throws the error:
> > 
> > // setting up PYTHONPATH
> > System.Environment.SetEnvironmentVariable("PYTHONPATH",@"C:\test;");
> > PythonEngine.Initialize();
> > PyObject module = PythonEngine.ImportModule("testModule");
> > PyObject returnObject = module.InvokeMethod("testMethod", new 
> > PyTuple());
> > 
> > 
> > 
> > Is this the correct way to import a module or can a fully specified 
> > path be used?  For example:
> > 
> > PythonEngine.ImportModule("C:\test\testModule.py");
> > 
> > 
> > PythonEngine.Initialize() initializes the interpreter --- what 
> > interpreter is initialized?  If Python is on the PATH, is that the 
> > interpreter initialized?
> > 
> > 
> > Thanks, I really appreciate any tips.
> > 
> > Joey J. Barrett
> > Investment Technology Group, Inc.
> > 
> >  
> > 
> > -----Original Message-----
> > From: pythondotnet-bounces at python.org
> > [mailto:pythondotnet-bounces at python.org] On Behalf Of Michael 
> > Eddington
> > Sent: Wednesday, June 06, 2007 11:09 AM
> > To: pythondotnet at python.org
> > Subject: Re: [Python.NET] Could you tell me how to call python from 
> > c#?
> > 
> > Yes, you can set the PYTHONHOME variable from .net prior to calling 
> > the initialize.  Many of the python runtimes set registry 
> keys or are 
> > located in default locations.
> > 
> > mike
> > 
> > On 6/6/07, Barrett, Joey <Joey.Barrett at itg.com> wrote:
> > >
> > > Thank you for your response, this is helpful.
> > >
> > > The methods called usually return lists or dictionaries and
> > sometimes
> > > other types too that need to be used within the C#.  In 
> the example
> > you
> > > provided the return value from InvokeMethod(), is a string
> > "fromPython",
> > > but I noticed InvokeMethod() actually returns a PyObject.
> > >
> > > How can I look at that PyObject and extract the returned values?
> > >
> > > The classes I use import many modules from a number of 
> locations on
> > disk
> > > that aren't known to the interpreter.
> > >
> > > Is there a way to add to the PYTHONPATH programmatically 
> in C# using
> > the
> > > Python for .net library, or would it be required to write 
> a wrapper 
> > > python module that adds to the path first?  Maybe there is
> > another way
> > > to handle this?
> > >
> > > Thank you again
> > >
> > > Joey J. Barrett
> > > Investment Technology Group, Inc.
> > >
> > > -----Original Message-----
> > > From: Karpenstein, Nissim (C-BASS)
> > > [mailto:Nissim.Karpenstein at C-BASS.COM]
> > > Sent: Wednesday, June 06, 2007 6:37 AM
> > > To: Barrett, Joey; pythondotnet at python.org
> > > Subject: RE: [Python.NET] Could you tell me how to call 
> python from
> > c#?
> > >
> > > I tried to post this to the list yesterday but it bounced
> > because of
> > > address issues...hopefully this will work:
> > >
> > > If you want to execute a python program from c-sharp you
> > can just use
> > > System.Diagnostics.Process to execute python.exe and you 
> don't need 
> > > python for .net.
> > >
> > > Python for .net is more appropriate for if you want to execute a
> > python
> > > function or create an instance of a python object and then
> > run methods
> > > and access attributes from your C# program.
> > >
> > > The example you linked to is OK, except that he modified the 
> > > Python.Runtime.Dll which is not necessary.
> > >
> > > If you had a Hello.py with a function called hello Like this:
> > >
> > > def hello():
> > >     return 'hello'
> > >
> > >
> > > You could do this in C#:
> > >
> > > PythonEngine.Initialize();
> > > PyObject helloModule = PythonEngine.ImportModule("Hello");
> > > String fromPython = helloModule.InvokeMethod("hello", new 
> > > PyTuple()).ToString(); PythonEngine.Shutdown();
> > >
> > > // now fromPython = "hello"
> > >
> > > If your function takes an argument:
> > >
> > > def returnArg(arg):
> > >     return arg
> > >
> > > PythonEngine.Initialize();
> > > PyObject helloModule = PythonEngine.ImportModule("Hello");
> > > String fromPython = helloModule.InvokeMethod("returnArg", new 
> > > PyObject[1] {new PyString("Test")}).ToString();
> > PythonEngine.Shutdown();
> > >
> > > // now fromPython = "test"
> > >
> > > ________________________________
> > >
> > >         From: pythondotnet-bounces at python.org 
> > > [mailto:pythondotnet-bounces at python.org] On Behalf Of 
> Barrett, Joey
> > >         Sent: Tuesday, June 05, 2007 8:11 PM
> > >         To: pythondotnet at python.org
> > >         Subject: Re: [Python.NET] Could you tell me how to
> > call python
> > > from c#?
> > >
> > >
> > >
> > >         Hi,
> > >
> > >
> > >
> > >         I also would be very interested in seeing some examples to
> > "call
> > > python from c#" using "Python for .NET".  I have dug around
> > Google and
> > a
> > > number of forums---I can't find anything except the post 
> from below.
> > I
> > > really hope I'm not missing the obvious somewhere.
> > >
> > >
> > >
> > >         IronPython is great but my needs require using a few c++ 
> > > extensions compiled for CPython (that can't be recompiled).
> > >
> > >
> > >
> > >         Also thanks in advance,
> > >
> > >
> > >
> > >         Joey J. Barrett
> > >
> > >         Investment Technology Group, Inc.
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >         Hello, PythonNet!
> > >
> > >
> > >         I'm looking for some sample code to call python from C#.
> > >         Actually, I'd like to execute python program(let say
> > 'Hello.py')
> > > from C#
> > >         with parameters.
> > >         Actually, I'm a newbie at both of languages. So, could you
> > give
> > > sample
> > >         source code? I was looking for some guide or source for
> > several
> > > days,
> > >         but I couldn't find it. What I've got so far from
> > googling is
> > >
> > >
> > http://mail.python.org/pipermail/pythondotnet/2003-November/00
> > 0037.html,
> > >
> > >         but I can't understand it and old one.
> > >
> > >         Thank you in advance.
> > >         Seungweon.
> > >
> > >
> > >
> > >
> > >
> > >
> > >
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> It is not intended as an offer or solicitation for the 
> purchase or sale of any financial instrument or as an 
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This message is for the named person's use only. This communication is for
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guaranteed. It is not intended as an offer or solicitation for the purchase
or sale of any financial instrument or as an official confirmation of any
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recommendation regarding, or opinion concerning, any security. It may
contain confidential, proprietary or legally privileged information. No
confidentiality or privilege is waived or lost by any mistransmission. If
you receive this message in error, please immediately delete it and all
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Securities products and services provided to Canadian investors are offered
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ITG Inc. and/or its affiliates reserves the right to monitor and archive
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