Mailman 3 January 2013 - Python.NET

Multithreading/multiprocessing
by Alan Macdonald May 5, 2025

May 5, 2025

Hello, has anyone successfully used multithreading or multiprocessing with Python.Net? I tried to multi-thread from the .Net side and the Python.Net libraries seem to have issues in the RunScript method. I had to take an implementation off the web of that method because the shipped method doesn’t seem to work. I then had a working multi-processing example from CPython that I tried from Python.Net but it gives an error 'module' object has no attribute 'argv' When trying to create a process pool by executing the line pool = Pool(processes=4) Is it possible to do multithreading or multiprocessing with Python.Net? Thanks, Alan

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Setting PYTHONPATH from code
by Sharon Rozenblum April 5, 2013

April 5, 2013

Hi! Can someone tell me how to set PYTHONPATH variable in code when working with Python.Runtime.dll without changing the value in the system variables before. Thanks SHARON ________________________________ PLEASE NOTE: The information contained in this electronic mail message is intended only for the use of the designated recipient(s) named above. If the reader of this message is not the intended recipient, you are hereby notified that you have received this message in error and that any review, dissemination, distribution, or copying of this message is strictly prohibited. If you have received this communication in error, please notify the sender by telephone or e-mail (as shown above) immediately and destroy any and all copies of this message in your possession (whether hard copies or electronically stored copies).

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Generics registration in the root namespace leads to exception
by Pierre-Yves Strub Jan. 30, 2013

Jan. 30, 2013

Hi, I hit a bug while using Python.NET in presence of generics in the root namespace (See attached C# file). I here attach a patch that solved the issue in my case. Bests, Pierre-Yves.

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Dynamic types of returns PyObject from the runtime
by Pierre-Yves Strub Jan. 30, 2013

Jan. 30, 2013

Hi, While playing with the .NET python runtime (see code bellow), I have been surprised to see that the dynamic type of all values returned by the runtime is PyObject. For instance, in the latter example, I would expect "sum" to be of dynamic type PyInt and to be able to write (sum :?> PyInt) instead of (PyInt.AsInt sum). Is it a "feature" of the runtime binding ? let entry () = PythonEngine.Initialize () use lock = new PythonEngineLock () in use builtin = PythonEngine.ImportModule ("__builtin__") in use data = new PyList (data |> Array.map (fun i -> new PyInt (i) :> PyObject)) in use sum = builtin.GetAttr("sum").Invoke([|data :> PyObject|]) in printfn "%A" (sum.GetType ()); printfn "%A" (sum.GetPythonType ()) Best, Pierre-Yves.

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How to pass a Type to a method?
by Daniel Krause Jan. 24, 2013

Jan. 24, 2013

I would like to use System.Array. The following code is running with iron python import clr import System from System import Array from System import Int32 from clr import GetClrType rows = 1 columns = 2 #method: Array.CreateInstance(Type, Int32, Int32) array = Array.CreateInstance(GetClrType(Int32), rows, columns) print array.GetLength(0) print array.GetLength(1) ouptput: 1 2 The same code throws an import error in python for .NET from clr import GetClrType ImportError: cannot import name GetClrType Is another syntax for python for .Net necessary? Or is there perhaps another method to pass a Type to a method?

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Problem with System.ArgumentException in call to method from dll
by Daniel Krause Jan. 24, 2013

Jan. 24, 2013

I want to use a method from an API to control a camera (xiApi.NETX64.dll). The method is described in two ways: // void GetImage( out WriteableBitmap image, int timeout) Description : This function acquires image and returns fills WritableBitmap object. Supports UNSAFE buffer policy mode. Parameters : out WriteableBitmap image : WPF BitmapSource to be filled. int timeout : Time interval required to wait for the image (in milliseconds). // void GetImage(WriteableBitmap image, int timeout) Description : This function acquires image and returns fills WritableBitmap object. Supports SAFE buffer policy mode. Parameters : WriteableBitmap image : WPF BitmapSource to be filled. int timeout : Time interval required to wait for the image (in milliseconds). // The code in a c#-sample looks like this (I skipped the initialisation of myCam, but if it helps I can provide the complete code): // using System.Windows.Media.Imaging; int timeout = 10000; BitmapSource myBitmapSrc; myCam.GetImage(out myBitmapSrc, timeout); // This code I can compile, and it is working. I tried to keep the python code as close as possible, but I get errors I do not understand: ## import clr import sys sys.path.append("C:\\Windows\\Microsoft.NET\\Framework64\\v4.0.30319\\WPF") clr.AddReference("PresentationCore") clr.AddReference("xiAPI.NETX64") from xiApi.NET import * from System.Windows.Media.Imaging import BitmapSource bitmapsrc = BitmapSource print bitmapsrc cam = xiCam() cam.OpenDevice(0) cam.SetParam(PRM.BUFFER_POLICY, BUFF_POLICY.SAFE) cam.SetParam(PRM.IMAGE_DATA_FORMAT, IMG_FORMAT.MONO8) cam.StartAcquisition() timeout = 1000 bitmapsrc = cam.GetImage(bitmapsrc, timeout) cam.StopAcquisition() ## Console output: <class 'System.Windows.Media.Imaging.BitmapSource'> Traceback (most recent call last): File "C:\Users\mdk\workspace\camera\testbitmap.py", line 17, in <module> bitmapsrc = cam.GetImage(bitmapsrc, timeout) System.ArgumentException: Das Objekt mit dem Typ "System.RuntimeType" kann nicht in den Typ "System.Drawing.Bitmap&" konvertiert werden. bei System.RuntimeType.TryChangeType(Object value, Binder binder, CultureInfo culture, Boolean needsSpecialCast) bei System.Reflection.MethodBase.CheckArguments(Object[] parameters, Binder b inder, BindingFlags invokeAttr, CultureInfo culture, Signature sig) bei System.Reflection.RuntimeMethodInfo.InvokeArgumentsCheck(Object obj, Bind ingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture) bei System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invok eAttr, Binder binder, Object[] parameters, CultureInfo culture) bei Python.Runtime.MethodBinder.Invoke(IntPtr inst, IntPtr args, IntPtr kw, M ethodBase info, MethodInfo[] methodinfo)

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Re: [Python.NET] How to use BitmapSource from System.Windows.Media.Imaging ?
by Daniel Krause Jan. 22, 2013

Jan. 22, 2013

Hi Jojo, thanks for your help. The following code is running (64bit-Windows): import clr import sys sys.path.append("C:\\Windows\\Microsoft.NET\\Framework64\\v4.0.30319\\WPF") clr.AddReference("PresentationCore") from System.Windows.Media.Imaging import BitmapSource bitmapsrc = BitmapSource print bitmapsrc Console output: <class 'System.Windows.Media.Imaging.BitmapSource'> Best regards Daniel 2013/1/21 Jojo Maquiling <jojo.maquiling(a)kadjo.org> > Hi, > In C#, the System.Windows.Media can just be shown if you add the > "PresentationCore" as part of your reference. The path of > PresentationCore.dll is in C:\Program Files (x86)\Reference > Assemblies\Microsoft\Framework\v3.0 if you are using Visual Studio > 2008. I think that might help if you add that as your reference in > clr.AddReference. I found some explanation in here - > > http://social.msdn.microsoft.com/Forums/en-US/windowswic/thread/fdfff143-c1… > I believe this will help you. > > HTH > > Thanks and best regards, > > Jojo Maquiling > > On Mon, Jan 21, 2013 at 3:40 AM, Daniel Krause > <m.daniel.krause(a)googlemail.com> wrote: > > I want to use BitmapSource from System.Windows.Media.Imaging > > (Documentation here: > > > http://msdn.microsoft.com/de-de/library/system.windows.media.imaging.bitmap… > > ) > > > > It would be great if someone could help me with this, as I do not have > yet > > much experience with python for .NET, and none at all with .NET itself. > > > > My test script: > > > > import clr > > clr.AddReference("System.Windows") > > import System.Windows > > bitmap = System.Windows.Media.Imaging.BitmapSource() > > > > The interpreter info is: > > Traceback (most recent call last): > > File "C:\Users\mdk\workspace\testbitmap.py", line 4, in <module> > > bitmapsrc = System.Windows.Media.Imaging.BitmapSource() > > AttributeError: Media > > > > I tried also: > > > > import clr > > clr.AddReference("System.Windows.Media") > > import System.Windows > > bitmapsrc = System.Windows.Media.Imaging.BitmapSource() > > > > > > Traceback (most recent call last): > > File "C:\Users\mdk\workspace\testbitmap.py", > > line 2, in <module> > > clr.AddReference("System.Windows.Media") > > System.IO.FileNotFoundException: Unable to find assembly > > 'System.Windows.Media'. > > bei Python.Runtime.CLRModule.AddReference(String name) > > > > And I also tried: > > > > import clr > > clr.AddReference("System.Windows") > > from System.Windows import Media > > bitmapsrc = Media.Imaging.BitmapSource() > > > > Traceback (most recent call last): > > File > > "C:\Users\mdk\workspace\lr_control\src\lr_control\camera\testbitmap.py", > > line 3, in <module> > > from System.Windows import Media > > ImportError: cannot import name Media > > > > _________________________________________________ > > Python.NET mailing list - PythonDotNet(a)python.org > > http://mail.python.org/mailman/listinfo/pythondotnet >

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How to use BitmapSource from System.Windows.Media.Imaging ?
by Daniel Krause Jan. 20, 2013

Jan. 20, 2013

I want to use BitmapSource from System.Windows.Media.Imaging (Documentation here: http://msdn.microsoft.com/de-de/library/system.windows.media.imaging.bitmap…) It would be great if someone could help me with this, as I do not have yet much experience with python for .NET, and none at all with .NET itself. My test script: import clr clr.AddReference("System.Windows") import System.Windows bitmap = System.Windows.Media.Imaging.BitmapSource() The interpreter info is: Traceback (most recent call last): File "C:\Users\mdk\workspace\testbitmap.py", line 4, in <module> bitmapsrc = System.Windows.Media.Imaging.BitmapSource() AttributeError: Media I tried also: import clr clr.AddReference("System.Windows.Media") import System.Windows bitmapsrc = System.Windows.Media.Imaging.BitmapSource() Traceback (most recent call last): File "C:\Users\mdk\workspace\testbitmap.py", line 2, in <module> clr.AddReference("System.Windows.Media") System.IO.FileNotFoundException: Unable to find assembly 'System.Windows.Media'. bei Python.Runtime.CLRModule.AddReference(String name) And I also tried: import clr clr.AddReference("System.Windows") from System.Windows import Media bitmapsrc = Media.Imaging.BitmapSource() Traceback (most recent call last): File "C:\Users\mdk\workspace\lr_control\src\lr_control\camera\testbitmap.py", line 3, in <module> from System.Windows import Media ImportError: cannot import name Media

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Problem to use a dll: System.ApplicationException: Error 1: OpenDevice: Invalid handle
by Daniel Krause Jan. 19, 2013

Jan. 19, 2013

I am trying to use a dll to control a camera. It is possible to use the dll with ironpython, but I fail to use it with python for .NET (CLR 4.0). (And I would like to use numpy as well, so I need python for .NET). Below follow a short test script, the python / ironpython versions and their console output when running the test script. Any hints are welcome. Thank you Daniel ######################################################## #test script "testcam.py" #1 for python for .NET import clr import sys sys.path.append("C:\\Users\\mdk\\workspace\\camera\\") clr.AddReference("xiAPI40.NET") from xiApi.NET import * cam = xiCam() cam.OpenDevice(0) print cam.GetParamString(PRM.DEVICE_NAME) #print device name ############### #console output showing the python version, #installed is .NET-support with pythonnet-2.0dev.clr4.0.win-amd64-py2.7.exe on Win7 64bit PS C:\Users\mdk\workspace\camera> python.exe Python 2.7.3 (default, Apr 10 2012, 23:24:47) [MSC v.1500 64 bit (AMD64)] on win32 Type "help", "copyright", "credits" or "license" for more information. ############### #running test script #1 with python, console output Traceback (most recent call last): File "C:\Users\mdk\workspace\camera\testcam.py", line 8, in <module> cam.OpenDevice(0) System.ApplicationException: Error 1: OpenDevice: Invalid handle at xiApi.NET.xiCam.throwException(Int32 errNum, String param) at xiApi.NET.xiCam.OpenDevice(Int32 DevID) ###################################################### #test script "testcam.py" #1 modified for ironpython, test script #2 import clr import sys sys.path.append("C:\\Users\\mdk\\camera\\") clr.AddReference("xiAPI40.NET.dll") from xiApi.NET import * cam = xiCam() cam.OpenDevice(0) print cam.GetParamString(PRM.DEVICE_NAME) #print device name ############### #console output showing the ironpython version PS C:\Users\mdk\workspace\camera> ipy.exe IronPython 2.7 (2.7.0.40) on .NET 4.0.30319.17929 Type "help", "copyright", "credits" or "license" for more information. >>> ############## #running test script #2 with ironpython, console output MQ013MG-E2

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Memory Type Problems
by Jeffrey Bush Jan. 17, 2013

Jan. 17, 2013

Hi, I have a library in C for compression. I made Python script for testing it, called using ctypes. Now, I am working on a .NET library for something very similar and would like to test it in the same way. However, I am getting lost in how to do some of the things with your library. The function I need to call looks like: public static long Compress(Memory input, Memory output) The Memory class is a wrapper around either managed byte arrays, void* (for efficiency), or memory mapped files. This allows a unified system for accessing general chunks of memory regardless if they are managed, native, or on the filesystem. They are created through static functions: public static Memory From(MemoryStream s, bool all = true)public static Memory From(byte[] b, bool readOnly = false)public static Memory From(byte[] b, long offset, long size, bool readOnly = false)public unsafe static Memory From(UnmanagedMemoryStream s, bool all = true)public unsafe static Memory From(void* b, long size, bool readOnly = false)public unsafe static Memory From(IntPtr b, long size, bool readOnly = false)public static Memory FromFile(string file, bool readOnly = false)public static Memory OfSize(long size) The only ones I can easily use are the last two (OfSize and FromFile). I have not yet figured out how to call the other ones properly. I don't seem to be able to allocate byte arrays with Array[Byte](10), it complains that 10 cannot be converted to System.Byte[] so it seems that it believes I am casting instead of creating a new array. No overloads seem to exist. So now here are my questions and the ctypes answer: - How do I construct a byte array? (ctypes.create_string_buffer) - How do I take a Python list/array and pass it as a pointer? (ctypes has this conversion happen automatically) - How do I turn a byte array into a useful Python list/array? As-is I can't use the Python-style indexers (except negative numbers). (The ctypes buffer works directly as a list, but also supports ".raw" and ".value") - How do I convert a pointer into a useful Python list/array? (ctypes casting allows this to work) Last point, although this is probably a limitation of .NET, but just to make sure. The default argument values can't be used, but it is possible that this isn't even in the assembly information and only works for source in the same module. Thanks, Jeff

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