[Python.NET] How to provide a variable of special type as method parameter
Daniel Krause
krausda at gmx.de
Mon May 14 12:41:05 EDT 2018
Hi,
I posted this question at stackoverflow some days ago:
https://stackoverflow.com/questions/50254745/how-to-provide-a-variable-of-special-type-as-method-parameter
I want to use a DLL with the help of Python for .NET (pythonnet).
The methods in this DLL require (pointer to?) variables as parameters.
I could figure out how to call a method and to provide an integer variable
as parameter.
I could not figure out how to provide such a parameter variable if a
special type is required (here: FTD2XX_NET.FTDI.FT_DEVICE_INFO_NODE[]).
Here is a code summary, and the results:
import clrimport sys
sys.path.append("C:\\Users\\[...]\\FTD2XX_NET_v1.1.0\\") # path to dll
clr.AddReference("System")
clr.AddReference("FTD2XX_NET")from FTD2XX_NET import FTDIfrom System
import UInt32
ftdi = FTDI()
if __name__ == '__main__':
# This method requires an integer as parameter, the code is working
# M:FTD2XX_NET.FTDI.GetLibraryVersion(System.UInt32@)
# summary: Gets the current FTD2XX.DLL driver version number.
# returns: FT_STATUS value from FT_GetLibraryVersion in FTD2XX.DLL
# param: name: LibraryVersion. The current library version.
version_ = 0 # empty variable to provide as parameter
ft_status, version = ftdi.GetLibraryVersion(version_)
print('status: {}\nversion: {}'.format(ft_status, version))
# prints
# status: 0
# version: 197140
# This method requires an FT_DEVICE_INFO_NODE[] as parameter, the code
is not working
# M:FTD2XX_NET.FTDI.GetDeviceList(FTD2XX_NET.FTDI.FT_DEVICE_INFO_NODE[])
# summary: Gets information on all of the FTDI devices available.
# returns: FT_STATUS value from FT_GetDeviceInfoDetail in FTD2XX.DLL
# param: name: devicelist.
# An array of type FT_DEVICE_INFO_NODE to contain the
device information
# for all available devices.
# no idea how to create the fitting parameter FT_DEVICE_INFO_NODE[]
devicelist_ = ftdi.FT_DEVICE_INFO_NODE() # empty variable to
provide as parameter
print(devicelist_.Flags, devicelist_.Type, devicelist_.ID,
devicelist_.LocId, devicelist_.SerialNumber,
devicelist_.Description, devicelist_.ftHandle)
# prints
# 0 0 0 0 None None 0
status, devicelist = FTDI.GetDeviceList(devicelist_)
print(devicelist)
# throws a TypeError: No method matches given arguments
Here <https://gist.github.com/Bovaz/aad3609abb70f23a208a> I found some
c#-code where FT_DEVICE_INFO_NODE[] and GetDeviceList are used in a method:
private int countDevices(){
FTDI.FT_STATUS ftStatus = FTDI.FT_STATUS.FT_OK;
ftStatus = myDevice.GetNumberOfDevices(ref ftdiDeviceCount);
if (ftStatus != FTDI.FT_STATUS.FT_OK)
return 0;
if (ftdiDeviceCount > 0)
{
//allocate device info list
ftdiDeviceList = new FTDI.FT_DEVICE_INFO_NODE[ftdiDeviceCount];
//populate list
ftStatus = myDevice.GetDeviceList(ftdiDeviceList);
if (ftStatus == FTDI.FT_STATUS.FT_OK)
{
return (int)ftdiDeviceCount;
}
else
return 0;
}
else
return 0;}
So my main problem seems to be the transition of ftdiDeviceList = new
FTDI.FT_DEVICE_INFO_NODE[ftdiDeviceCount]; to valid python for .NET - code.
It would be great if someone could provide some hints.
Thanks
Daniel
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