I've been experimenting with the win32com extensions to control an RCX
programmable brick using the Spirit.OCX provided by LEGO. My first
attempts have been succesful: I've been able to command the RCX quite
easily by calling the functions prototyped in the module generated by
makepy.
However, I've had two problems:
1. EARLY BINDING: NO GO
I've been unable to early-bind the COM object for Spirit.OCX. When I run
the code below, communications with the RCX work, and the file
D6CD40C0-A522-11D0-9800-D3C9B35D2C47x0x1x0.py is generated at
C:\Python21\win32com\gen_py as expected, but the string representation
of the rcx object (line 7 below) is <COMObject SPIRIT.SpiritCtrl.1>
instead of someting like <win32com.gen_py.???> as shown on page 205 of
Mark Hammond's Python Programming on Win32 and on the "Quick Start to
Client side COM and Python" online help page. One consequence of this is
that I cannot use the COM enum constants generated by makepy.
-- LISTING 1 ---------------
# next 2 lines generated by makepy.py -i ([Hammond], p.204)
from win32com.client import gencache
gencache.EnsureModule('{D6CD40C0-A522-11D0-9800-D3C9B35D2C47}', 0, 1, 0)
import win32com.client
rcx = win32com.client.Dispatch('SPIRIT.SpiritCtrl.1')
print repr(rcx)
print rcx.__class__
rcx.ComPortNo = 2 #COM2
rcx.LinkType = 0 #INFRARED
rcx.PBrick = 1 #RCX
print 'InitComm:', rcx.InitComm()
print 'TowerAndCableConnected:', rcx.TowerAndCableConnected()
print 'PBAliveOrNot:', rcx.PBAliveOrNot()
print 'CloseComm:', rcx.CloseComm()
----------------------------
2. HOW TO SUBCLASS A COM CLASS?
I need to handle some events generated by the OCX. The auto-generated
D6CD40C0... module contains commented-out prototypes for functions like
this:
# def OnDownloadDone(self, ErrorCode=defaultNamedNotOptArg,
DownloadNo=defaultNamedNotOptArg):
Now, I don't know where to define those functions im my code. I suppose
I should not edit the D6CD40C0... module, since it is auto-generated. I
would like to create a subclass of the OCX class, but I don't know how,
since the __class__ of the rcx object returned by
win32com.client.Dispatch('SPIRIT.SpiritCtrl.1') is
win32com.client.CDispatch.
I also tried to use the GetClassForProgID function of the
win32com.client.gencache module, which gave me a class described as:
<class win32com.gen_py.D6CD40C0-A522-11D0-9800-D3C9B35D2C.Spirit at
0081811C>. This looked promising. But trying to create an instance of
that class generated the following traceback:
Traceback (most recent call last):
File "spirit_test_class.py", line 10, in ?
rcx = MySpirit()
File
"c:\python21\win32com\gen_py\D6CD40C0-A522-11D0-9800-D3C9B35D2C47x0x1x0.py",
line 407, in __init__
self.__dict__["_dispobj_"] = self.default_interface(oobj)
TypeError: object is not callable:
'{D6CD40C1-A522-11D0-9800-D3C9B35D2C47}'
Here is the code I used in this attempt:
-- LISTING 2 ---------------
from win32com.client import gencache
SpiritClass = gencache.GetClassForProgID('SPIRIT.SpiritCtrl.1')
print repr(SpiritClass)
class MySpirit(SpiritClass):
def OnDownloadDone(self, ErrorCode=None, DownloadNo=None):
print 'ErrorCode: %s; DownloadNo: %s' % (ErrorCode, DownloadNo)
rcx = MySpirit()
----------------------------
Best regards,
Luciano
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